PHY010 HW Questions - Final Exam Review

Fancy makeup mirrors allow users to choose either fluorescent or incandescent illumination to match the lighting in which they'll be seen. Why does the type of illumination affect their appearances? Since incandescent light has less blue than fluorescent light, incandescent light reflected from a person's skin would also have less blue in it. Since incandescent light has more red than fluorescent light, incandescent light reflected from a person's skin would also have more red in it. Since incandescent light has more red than fluorescent light, incandescent light reflected from a person's skin would have less blue in it. All of the above choices are correct.

All of the above choices are correct. Since incandescent light has less blue than fluorescent light, incandescent light reflected from a person's skin would also have less blue in it. Skin can't reflect light that isn't there.

Sports photographers often use large aperture, long focal length lenses. What limitations do these lenses impose on the photographs? Their depths of focus are relatively small. Their depths of focus are relatively large. There are no limitations to these cameras. None of the above choices are correct.

Their depths of focus are relatively small. If the lens diameter (or aperature) is larger, light must come together from a larger range of angles making focusing more critical than if the light is coming in all in the same direction (as is the case for a very small lens) These lenses are good to use to take an elarged picture (telephoto) of an object with 100% clarity (only if the image of the object appears perfectly in the focus). All other objects will seem blurry because their images will appear away from the perfect focusing point. As a shorter summary, we can say that these lenses have a small depth of focus.

When you drop the north pole of a permanent magnet onto an aluminum sheet, it falls slightly slower than normal. The magnet is being repelled by the aluminum because aluminum has a net south magnetic pole that repels any approaching north poles. current induced in the aluminum by the approaching north pole produces a repelling north pole on the aluminum's surface. aluminum is positively charged and repels approaching magnetic poles. aluminum has a net north magnetic pole that repels any approaching north poles.

current induced in the aluminum by the approaching north pole produces a repelling north pole on the aluminum's surface. The approaching north pole develops an electric field because it's moving and causes currents to flow through the aluminum. These currents are magnetic and, in accordance with Lenz's law, they oppose the field change that causes them—they repel the approaching north pole.

The steel ball in a pinball game rolls around a flat, tilted surface. If you flick the ball straight uphill, it gradually slows to a stop and then begins to roll downhill. Which direction is the ball accelerating (a) as it rolls uphill? (b) as it rolls downhill? (a) downhill; (b) uphill (a) uphill; (b) downhill (a) zero; (b) downhill (a) downhill; (b) downhill

(a) downhill; (b) downhill As the steel ball rolls uphill, the velocity gradually decreases and finally the ball stops, thus, the acceleration will be in the opposite direction of motion (that is downhill). After the stop, the ball will start rolling downhill by an increasing velocity, thus, the acceleration in this case will be in the same direction as the motion (downhill again).

Most commercial airliners have static dissipaters on their wingtips. These sharp metal spikes extend from the end of each metal wing and point toward the rear of the plane. Suppose a plane had just flown through a negatively charged cloud and acquired a large negative charge. It is now flying through neutral air. Which of the following should you expect to happen near the static dissipaters? A corona discharge at the dissipater tips will spray positive charge into the air. Any charge on the dissipaters will flow toward the wings, leaving the dissipaters neutral. A corona discharge at the dissipater tips will spray negative charge into the air. Nothing, because the air is neutral.

A corona discharge at the dissipater tips will spray negative charge into the air. The negative charge on the airplane will push a substantial amount of negative charge onto the tip of a dissipater. There the closely packed negative charges will repel one another so strongly that they will push each other into the air as a corona discharge.

Which of the following can cause a charged particle to accelerate? An electric field only A gravitational field only A neutron field only A gravitational field and an electric field

A gravitational field and an electric field A charged particle has mass as well as electric charge. It is then subject to two forces: gravity and electric. It will accelerate according to acceleration = Force / mass. In the case of gravity, the Force is the particle's weight. In the case of electricity it is related to magnitude of the charges and the distances between the charges (Force ~ (q1 * q2)/r^2). The total force will the the vector sum of the two forces.

Why is it important that the filament of a lightbulb have a much larger electrical resistance that the supporting wires that carry current to and from that filament? A larger electrical resistance has a smaller voltage drop and thus consumes less electrical power. A larger electrical resistance has a larger voltage drop and thus consumes less electrical power. A larger electrical resistance has a larger voltage drop and thus consumes more electrical power. A larger electrical resistance has a smaller voltage drop and thus consumes more electrical power.

A larger electrical resistance has a larger voltage drop and thus consumes more electrical power. The filament's larger resistance ensures that it experiences the main voltage drop and receives most of the current's electrical power

To read the magnetic strip on an ID or credit card, you must swipe it quickly past a tiny coil of wire. Why must the card be moving for the coil system to read it? A moving magnet will create enough charges in the coil so that the magnetic strip can be read. A moving magnet will induce a current in the coil so that the magnetic strip can be read. A moving magnet will ensure that there is no electric field inside the coil so that the magnetic strip can be read. A moving magnet will destroy enough charges in the coil so that the magnetic strip can be read.

A moving magnet will induce a current in the coil so that the magnetic strip can be read. Only a moving magnet or changing magnetic field will produce the electric field necessary to push currents through coil inside the playback head.

Porous, unglazed ceramics can absorb water and moisture. Why are they unsuitable for use in a microwave oven? Water molecules trapped in the ceramics would absorb microwaves and the ceramic would become extremely hot. Water molecules trapped in the ceramics would turn and bump into one another over and over again because of the fluctuating electric field of the microwave and the ceramic would become extremely hot. Water molecules trapped in the ceramics would convert the energy of the microwaves into thermal energy and the ceramic would become extremely hot. All of the above choices are correct.

All of the above choices are correct. Water trapped in the ceramic would absorb microwaves, and the ceramic would become extremely hot. It might even shatter.

Why are most microwave TV dinners packaged in plastic rather than aluminum trays? Aluminum trays would reflect the microwaves which would result in improperly cooked food. Aluminum trays would transmit the microwaves which would result in improperly cooked food. Aluminum trays would refract the microwaves which would result in improperly cooked food. All of the above choices are correct.

Aluminum trays would reflect the microwaves which would result in improperly cooked food Microwave doesn't go through aluminum tray, instead, it will be reflected (absorbed and readmitted). Thus, the food sealed inside the aluminum tray cannot be properly cooked.

When you kick a soccer ball, which pushes on the other harder: your foot or the soccer ball? The answer depends on additional factors not mentioned here. Both push equally. Your foot pushes harder. The soccer ball pushes harder.

Both push equally Because of the Newton's 3rd law. "for every action, there is an equal but opposite reaction"

You're cutting wood with a handsaw. You have to push the saw away from you as it moves away from you and pull the saw toward you as it moves toward you. When are you doing positive work on the saw? Only while pulling. You do not do positive work on the saw at any point. Both while pushing and pulling. Only while pushing.

Both while pushing and pulling As you move the handsaw away from you, you exert a force on the handsaw away from you. Since both of the displacement and force vectors are in the same direction as explained above, the work done on the saw will be positive. Similarly, the work will be also positive when you move the saw toward you because both force and displacement are again in the same direction

What is the main reason a DVD can hold more information than a CD, aside from the number of layers of data storage medium? DVD's use polarized light. CD's are diffraction limited. DVD's use shorter-wavelength light than CD's. CD light is circularly polarized.

DVD's use shorter-wavelength light than CD's CD players use infrared light while DVD's use red light. Electromagnetic waves cannot read structures much smaller than their own wavelength and infrared light has a larger wavelength than red light. New blue light lasers are being utilized to hold even more information. (DVD's also utilize compression, which CD's do not).

When your receiver is too far from an AM radio station, you can only hear the loud parts of the transmission. When it's too far from an FM station, you lose the whole sound all at once. Explain the reasons for this difference. In an AM transmission, the radio wave is strongest during the loudest portions of the broadcast but in an FM transmission, the radio wave intensity is constant. In an AM transmission, the radio wave intensity is constant but in an FM transmission, the radio wave is strongest during the loudest portions of the broadcast. In both AM and FM transmissions, the radio wave is strongest during the loudest portions of the broadcast. In both AM and FM transmissions, the radio wave intensity is constant.

In an AM transmission, the radio wave is strongest during the loudest portions of the broadcast but in an FM transmission, the radio wave intensity is constant. The amplitude (intensity) of a radio wave varies for an AM radio station (such as, the amplitude of the wave is bigger for louder portion of the broadcast), however, it is constant for an FM radio station. As a result, if you are standing at a place really far from the radio transmitting antenna, then it is still possible to hear only the louder sounds for an AM station, however, the reception will be totally lost for an FM station.

After you extract two pieces of adhesive tape from a tape dispenser, those pieces will repel one another. Explain their repulsion. Each piece of tape will acquire like charges while being extracted from the tape dispenser. Each piece of tape will acquire opposite charges while being extracted from the tape dispenser. One piece of tape will have a greater net charge which would repel the other piece. The adhesive tape is sticky so they would always attract.

Each piece of tape will acquire like charges while being extracted from the tape dispenser. Each piece of tape will have like charges after the extraction and like charges repel each other.

The two prongs of a power cord are meant to carry current to and from a lamp. If you were to plug only one of the prongs into an outlet, the lamp wouldn't light at all. Why wouldn't it at least glow at half its normal brightness? No current flows because by using only one prong, an open circuit is created and thus the lamp cannot glow. No current flows because by using only one prong, charges in the lamp are destroyed and thus the lamp cannot glow. No current flows because by using only one prong, a closed circuit is created and thus the lamp cannot glow. No current flows because by using only one prong, charges cannot be created in the lamp to make it glow.

No current flows because by using only one prong, an open circuit is created and thus the lamp cannot glow. The lamp needs two connections to the power company: one through which to receive charge and the other through which to return that charge to the power company

As you jump across a small stream, does a horizontal force keep you moving forward? If so, what is the force? Yes, there is a horizontal force. Gravity is that force. Yes, the horizontal force of the leap pushes you across the stream. No, there is no horizontal force. You continue to move forward because of inertia. Yes, there is a horizontal force. Inertia is that force.

No, there is no horizontal force. You continue to move forward because of inertia. A small stream acts like a frictionless surface. And your jump is similar to a small push to start the motion while you are skating on the ice. You keep moving forward because of not an existing forward force but your inertia.

Some of the laser light striking a DVD's reflective layer hits the flat region around a pit and reflects back toward the photodiode. How does this reflected wave actually reduce the amount of light detected by the photodiode? Waves reflected by the pits and flats undergo refraction. Waves reflected by the pits and flats undergo total internal reflection. Waves reflected by the pits and flats undergo constructive interference. None of the above choices are correct.

None of the above choices are correct. Waves reflected by pits and flats interfere destrictively.

Thermal energy can shift some of the electrons in a hot semiconductor from valence levels to conduction levels. What effect do these shifts have on the semiconductor's ability to conduct electricity? Semiconductor's ability to conduct electricity increases. Semiconductor's ability to conduct electricity decreases. Semiconductor's ability to conduct electricity doesn't change

Semiconductor's ability to conduct electricity increases. Since there are more electrons available in the conduction level at high temperatures, the electric conductivity of a semiconductor will be increased.

Suppose you are driving north and suddenly hit your brakes to avoid a dog in the road. As you come to a stop your acceleration is directed South Nowhere because acceleration is a scalar Downwards North

South Hitting the brakes will slow you down in which case the acceleration is in the opposite direction of motion. Since you are driving north, the acceleration will be in south direction.

An ion generator clears smoke from room air by electrically charging the smoke particles. Why will those charged smoke particles stick to the walls and furniture? The charged smoke particles will never stick to a neutral surface; only to a surface that has an opposite charge. The charged smoke particles polarize the neutral surfaces. The charged smoke particles will induce an opposite charge in the neutral surfaces. The charged smoke particles will oppositely charge the neutral surfaces when they come in contact.

The charged smoke particles polarize the neutral surfaces. Although the walls and furniture are neutral, the charged smoke particles will polarize the surfaces by accumulating the opposite charges (in the wall or furniture) on the surface while forcing like charges (in the wall or furniture) to stay away from the surface. As a result, the charged smoke particles will stick to the surfaces.

Which way does the electric field point around the positive terminal of an alkaline battery? The electric field points towards the positive terminal's surface. The electric field does not leave the inside of an alkaline battery. The electric field is a scalar quantity and therefore has no direction. The electric field points away from the positive terminal's surface.

The electric field points away from the positive terminal's surface. As we should always remember, E. Field lines are pointed away from the positive charges (Also remember that the E. Field lines are pointed towards the negative charges).

Hammering or heating a permanent magnet can demagnetize it. What happens to the magnetic domains inside it during these processes? The magnetic domains will lose their uniform orientations and become more randomly oriented. The magnetic domains of any permanent magnet cannot move. The magnetic domains will change their orientations and become more uniformly oriented. The magnetic domains will grow in size.

The magnetic domains will lose their uniform orientations and become more randomly oriented. A permanent magnet has a uniform magnetic orientation (all magnetic dipoles are oriented in the same way). Hammering or heating will kill this uniform orientation and new domains which are randomly oriented will be created.

Do more magnetic flux lines begin or end on a button magnet, or are those numbers equal? There are no magnetic flux lines near a button magnet. More magnetic flux lines end on a button magnet. The magnetic flux lines beginning and ending on a button magnet are equal. More magnetic flux lines begin on a button magnet.

The magnetic flux lines beginning and ending on a button magnet are equal. Each magnetic flux line begins from the north pole of a magnetic material and ends at the south pole. Therefore, the numbers are equal.

When astronauts walked on the surface of the moon, they could see the stars even though the sun was overhead. Why can't we see the stars while the sun is overhead? The scattered light from the sun is so bright that it overwhelms the dim light from the stars. Light from the stars does not reach the earth while the sun is out. The stars do not emit any light during the day. None of the above choices are correct.

The scattered light from the sun is so bright that it overwhelms the dim light from the stars. Charged particles in the atosphere act like little antennas, and preferentially scatter (absorb and re-emit) blue light over red light. While the wavelength of the light is far smaller than 1/2 wavelength (~1000 times smaller), which is the ideal antenna size, enough light scatters to dominate overwhelm the light from stars which are far away.

Compare how a potato cooks in a microwave oven with how it cooks in an ordinary oven. In a microwave oven, the potato's water absorbs microwaves and that microwave energy becomes thermal energy and the potato's temperature rises nonuniformly with the middle of the potato last to become cooked. In an ordinary oven, heat flows gradually into the potato through its surface and its temperature rises uniformly. In a microwave oven, heat flows gradually into the potato through its surface and its temperature rises uniformly. In an ordinary oven, the potato's water absorbs the heat energy and the potato's temperature rises nonuniformly with the middle of the potato last to become cooked. In a microwave oven, heat flows gradually into the potato through its surface and its temperature rises nonuniformly with the middle of the potato last to become cooked. In an ordinary oven, the potato's water absorbs the heat energy and the potato's temperature rises uniformly. In a microwave oven, the potato's water absorbs microwaves and that microwave energy becomes thermal energy and the potato's temperature rises uniformly. In an ordinary oven, heat flows gradually into the potato through its surface and its temperature rises nonuniformly with the middle of the potato last to become cooked.

In a microwave oven, the potato's water absorbs microwaves and that microwave energy becomes thermal energy and the potato's temperature rises uniformly. In an ordinary oven, heat flows gradually into the potato through its surface and its temperature rises nonuniformly with the middle of the potato last to become cooked. In a microwave oven, the cooking of a potato is uniform (all the water molecules found in different parts of the potato will start rotating back and forth at the same time because of the oscillating/changing electric field of microwave). In an ordinary oven, the thermal energy will be absorbed by the surface first and it will start moving towards the center (nonuniform cooking).

A MOSFET doesn't change instantly from a perfect insulator to a perfect conductor as you vary the charge on its gate. With intermediate amounts of charge on its gate, the MOSFET acts as a resistor with a moderate electrical resistance. This flexibility allows the MOSFET to control the amount of current flowing in a circuit. Explain why a MOSFET becomes warm as it controls that current. When current flows through a MOSFET, the MOSFET acts as a resistor which results in a voltage drop across the MOSFET and thus some of the current's energy is converted into thermal energy. When current flows through a MOSFET, the MOSFET acts as a resistor which results in a voltage rise across the MOSFET and thus some of the thermal energy is converted into electrical energy. When current flows through a MOSFET, the MOSFET acts as a resistor which results in a voltage rise across the MOSFET and thus some of the current's energy is converted into thermal energy. When current flows through a MOSFET, the MOSFET acts as a resistor which results in a voltage drop across the MOSFET and thus some of the thermal energy is converted into electrical energy.

When current flows through a MOSFET, the MOSFET acts as a resistor which results in a voltage drop across the MOSFET and thus some of the current's energy is converted into thermal energy.

Explain the strategy of putting highly radioactive materials in a storage place for many years as a way to make them less hazardous. That wouldn't work for chemical poisons, so why does it work for radioactive materials? With time, radioactive nuclei will exponentially decay and the materials become less and less hazardous. With time, radioactive nuclei will linearly decay and the materials become less and less hazardous. With time, radioactive nuclei will logarithmically decay and the materials become less and less hazardous. All of the above choices are correct.

With time, radioactive nuclei will exponentially decay and the materials become less and less hazardous.

An extremely fast-moving charged particle traveling in a magnetic field can radiate X-rays, a phenomenon known as synchrotron radiation. Why is the magnetic field essential to this emission? Without the magnetic field, the charged particle would travel at a constant velocity and would not radiate electromagnetic waves because of its contant velocity. Without the magnetic field, the charged particle would come to a stop and would not radiate electromagnetic waves because of its zero velocity. Without the magnetic field, the charged particle would accelerate and would not radiate electromagnetic waves because of its acceleration. Without the magnetic field, the charged particle would turn around and therefore not radiate electromagnetic waves.

Without the magnetic field, the charged particle would travel at a constant velocity and would not radiate electromagnetic waves because of its contant velocity. Without the magnetic field, the charged particle would travel at constant velocity (at constant speed along a straight path) and would not radiate electromagnetic waves.

If you're taking a photographic portrait of a friend and want objects in the foreground and background to appear blurry, how should you adjust the camera's aperture and shutter speed? You should use the largest available aperture and a short shutter speed. You should use the smallest available aperture and a short shutter speed. You should use the largest available aperture and a long shutter speed. You should use the smallest available aperture and a long shutter speed.

You should use the largest available aperture and a short shutter speed. If the lens diameter (or aperature) is larger, light must come together from a larger range of angles making focusing more critical than if the light is coming in all in the same direction (as is the case for a very small lens). The larger diameter allows more light to be collected so that it can have a fast shutter speed, but it will have a small depth of focus.

An engineer at the company you are working for has just reported finding an unusual electromagnetic wave. This wave consists only of an electric field, with no magnetic field accompanying it. You are certain that the engineer is mistaken because an electromagnetic wave must have a magnetic field that changes with time to produce its electric field. electromagnetic waves always contain both electric charges and magnetic poles, and magnetic poles are accompanied by magnetic fields. electromagnetic waves contain moving electric charges and charges produce magnetic fields when they move. while waves consisting only of electric fields are common and travels indefinitely through space, they are known as "electric waves," not "electromagnetic waves."

an electromagnetic wave must have a magnetic field that changes with time to produce its electric field. Electromagnetic waves consist of an electric field, a magnetic field, and nothing else. An accelerating charge launches an electromagnetic wave and travel forever in free space transferring energy back and forth between electric and magnetic fields. The electric field changes in time causing a magnetic field to change with time, causing an electric field to change with time, etc.

If electrons had four different internal states that could be distinguished from one another, how many electrons could occupy the same orbital without violating the Pauli exclusion principle? 4 electrons any number from 4 to 8 electrons any number from 0 to 8 electrons any number from 0 to 4 electrons

any number from 0 to 4 electrons Up to four electrons could then occupy the same level. The Pauli exclusion principle only prevents indistinguishable Fermi particles from occupying the same level. With four different distinguishable electrons, a level can hold up to four electrons.

Fission chain reactions in uranium are sustained by neutrons, each of which is released by one fission and may induce a subsequent fission. Each fission also releases other particles, which include protons. However, proton-containing fission fragments are not as effective at causing subsequent fissions because they are not massive enough to cause fissions in uranium. are repelled as they try to approach other uranium nuclei. do not exert any forces on the uranium nuclei they encounter. are not hot enough to make a uranium nucleus boil.

are repelled as they try to approach other uranium nuclei.

Your cat has chewed the cord to your desk lamp and has created a short circuit an electric connection from one wire to the other inside the cord. When you plug the lamp into the electric outlet, current will flow alternately through the bulb and through the short circuit, so that the bulb will blink on and off rapidly. excessive current will pass through the bulb and the bulb will glow very brightly. current will bypass the bulb and the bulb will not light up. the current will begin to flow backward through the bulb so that it glows at half its normal brightness

current will bypass the bulb and the bulb will not light up. The short circuit will provide a more effective path for the current heading toward the bulb through one wire and leaving through the other. Instead of flowing through the bulb's filament and lighting it up, most of the current will bypass the bulb by flowing through the short circuit.

Increasing the diameter of a camera lens, while keeping its focal length unchanged, does more than just brighten the image on the film so that you can use a shorter exposure. It also decreases the depth of focus so that objects at different distances will no longer all be in focus at once. increases the size of the image on the film so that you get a close up. decreases the size of the image on the film so that you get a wide angle view. increases the depth of focus so that objects at different distances will all be in focus at once.

decreases the depth of focus so that objects at different distances will no longer all be in focus at once. If the lens diameter is larger, light must come together from a larger range of angles making focusing more critical than if the light is coming in all in the same direction (as is the case for a very small lens).

When you drop a strong magnet through the center of a copper pipe, the magnet descends slowly because its motion causes currents to flow in the pipe and those currents repel the magnet. descends slowly because it is attracted to the magnetic copper metal. descends rapidly because its motion causes currents to flow in the pipe and those currents attract the magnet. falls at the usual rate because copper metal is nonmagnetic.

descends slowly because its motion causes currents to flow in the pipe and those currents repel the magnet. The falling magnet experiences a magnetic drag force--its motion causes electric currents to flow in the copper pipe and, according to Lenz's law, these currents exert repulsive magnetic forces on the falling magnet. The magnet has trouble falling through the pipe and descends slowly.

A xerographic copier uses a special photoconductor surface that allows light from an original document to control the placement of black powder on white paper. The photoconductor only conducts electricity when it's exposed to light because, in the dark, the photoconductor doesn't contain any electrically charged particles. electrons in the photoconductor completely fill its valence levels and can't shift from one level to another in order to transport charge through the material. the photoconductor contains only negatively charged particles. the photoconductor contains only positively charged particles.

electrons in the photoconductor completely fill its valence levels and can't shift from one level to another in order to transport charge through the material. The electrons in a semiconductor, like those in an insulator, are prevented from responding to electric fields because they have no nearby empty levels into which they can shift. The whole arrangement of electrons is rigid and immobile because of this constraint

If you are backing up but slowing down, your acceleration is directed forwards nowhere to the left backwards

forwards Applying the brakes will slow you down in which case the acceleration is in the opposite direction of motion.

An FM radio station instructs your radio receiver how to move its speaker cone by varying the amount of electric charge it pushes up and down its antenna. amplitude of the radio wave it produces. strength of the electric and magnetic fields in the radio wave it produces. frequency of the radio wave it produces.

frequency of the radio wave it produces. FM means frequency modulation. Air pressure fluctuations are encoded as small changes in the frequency of the radio wave, while the amplitude does not vary

Your class is rather unhappy with the instructor, and they pitch in and decide to fund a sabbatical for him to go to Mars. Unbeknownst to the students the following semester, the instructor has made long distance course arrangements so the "show can go on". The instructor begins talking about mass, weight and related things. He correctly makes which following statement: his weight is still essentially unchanged but his mass is less than on earth. his weight and mass have both changed significantly. his mass is still essentially unchanged but his weight is less than on earth. neither his weight nor his mass have changed much.

his mass is still essentially unchanged but his weight is less than on earth. Mass of an object is an unchanging scalar quantity so it remains the same for an object everywhere in the universe. However, the weight is a vectoral quantity proportional to the gravity. Since the gravity on earth is greater than that on Mars , the weight will be more here on earth.

In a typical laser, the right color of light bounces back and forth between two mirrors and is ignored by the laser medium. is amplified by the mirrors. is amplified by the excited atoms in the laser medium. is de-amplified by the laser medium.

is amplified by the excited atoms in the laser medium When the laser medium is placed between the two mirrors, there is a chance that a photon, emitted spontaneously by one of the excited systems, will bounce off a mirror and return toward the laser medium. As that returning photon passes through the laser medium, it's amplified.

A projectile is thrown directly upward and caught again. At the top of its path its vertical velocity is zero its acceleration changes it stops accelerating its horizontal velocity changes

its vertical velocity is zero In a projectile motion, the vertical velocity component is upward at the beginning and starts decreasing until it eventually becomes zero at the maximum point. Then, the vertical component of the velocity starts increasing in downward direction as the object losses its height (Please also remember that the horizontal component of velocity remains the same in forward direction).

Laser light exhibits much stronger interference effects than light from a flashlight. This is because laser light has a much shorter wavelength than light from a flashlight. laser light is both coherent and monochromatic. laser light carries much more energy than light from a flashlight. laser light travels as waves while light from a flashlight travels as particles.

laser light is both coherent and monochromatic. Laser light consists of a large number of absolutely identical photons which travel as one giant wave, leave the potential for large interference effects as each laser photon can interfere with every other laser photon while each flashlight photon can only interfere with itself.

A photoconductor's electrical properties go from insulating to conducting when it is exposed to light because, light lowers the energy of the conduction levels eliminating the energy gap. light allows extra electrons to move into the conduction band giving the semiconductor a negative charge. light supplies the energy needed to move electrons from the valence band to the conduction band. light allows extra electrons to move out of the valence band giving the semiconductor a positive charge.

light supplies the energy needed to move electrons from the valence band to the conduction band. A photoconductor is insulating in the dark because its valence band is full and its conduction band is empty. No electrons can move in response to an electric field. However, when you shine light on the photoconductor, light energy promotes some of the valence level electrons to conduction levels and suddenly the electrons can move about

For a nuclear weapon to explode normally, the fissionable material in its core must be assembled very quickly. For technical reasons, a nuclear bomb developed by a terrorist group would probably not achieve such rapid assembly. As a result of its slow assembly, such a bomb would explode powerfully, but at a relatively unpredictable moment. To shorten the time window over which the explosion could occur, external nuclear triggers would be needed. not explode because there would not be enough momentum present to push the neutrons into the fissionable nuclei of its core. overheat and push itself apart during the assembly, producing only a weak explosion. not explode because there would not be enough energy present to push the neutrons into the fissionable nuclei of its core.

overheat and push itself apart during the assembly, producing only a weak explosion.

A battery works because it pumps positive charge from its negative terminal to its positive terminal. creates positive charge. creates negative charge. pumps positive charge from its positive terminal to its negative terminal.

pumps positive charge from its negative terminal to its positive terminal. Batteries are "pumps" for electric charge. A battery takes an electric current (moving charge) entering its negative terminal and pumps that current to its positive terminal. In the process, the battery adds energy to the current and raises its voltage (voltage is the measure of energy per unit of electric charge). A typical battery adds 1.5 volts to the current passing through it. As it pumps current, the battery consumes its store of chemical potential energy so that it eventually runs out and "dies.

A dolphin can leap several meters above the ocean's surface. Gravity does not stop the dolphin from leaving the water because..? the water pushes the dolphin out. the surface of the water breaks the pull of gravity. the dolphin has inertia as it approaches the surface. gravity has no effect in the water.

the dolphin has inertia as it approaches the surface The initial inertia of the dolphin helps itself to leave the water, however, the gravity will start acting on the dolphin after it gets in to air and pull it back to the surface/water again.

Many sophisticated cameras have zoom lenses. When you select the telephoto setting, the objects in front of you appear much closer. In this setting, the focal length of the lens is shorter than normal. the aperture of the lens is larger than normal. the focal length of the lens is longer than normal. the aperture of the lens is smaller than normal.

the focal length of the lens is longer than normal A telephoto has a small curvature or large focal length, and is located further from the film giving a more distance for the image to enlarge.

You have covered a grounded metal surface with a layer of photoconductor. Working in the dark, you sprinkle negative charge onto this surface. If you now expose only the left half of the photoconductor to light, you will find that... negative charge flows from the right side of the photoconductor to the left and both sides become neutral. the left half becomes neutral while the right half remains negatively charged. the right half becomes neutral while the left half remains negatively charged. nothing happens because there is no changing magnetic field.

the left half becomes neutral while the right half remains negatively charged Wherever light strikes the photoconductor, it transforms from an insulator into a conductor. The charge then migrates through it and leaves its surface. By exposing the left half of the photoconductor to light, you allow its local charge to leave and it becomes neutral.

When laser light reflects from a soap bubble, its photons can interfere with one another. In contrast, when sunlight reflects from a soap bubble, each photon can interfere only with itself. The reason for this difference is that the photons in a laser beam are all part of a single wave, while those in sunlight are independent waves. the photons in a laser beam have both electric and magnetic fields, while those in sunlight have only electric fields. the photons in a laser beam have both electric and magnetic fields, while those in sunlight have only magnetic fields. the photons in a laser beam are both vertically and horizontally polarized, while those in sunlight are only vertically polarized.

the photons in a laser beam are all part of a single wave, while those in sunlight are independent waves. Laser light consists of a large number of absolutely identical photons which travel as one giant wave, leave the potential for large interference effects as each laser photon can interfere with every other laser photon.

One type of home coffee grinder has a small blade that rotates very rapidly and cuts the coffee beans into powder. Nothing prevents the coffee beans from moving. The reason the beans don't get out of the way when the blade begins to push on them is they have inertia. the beans are stuck together. the blades aren't strong enough to make them move. gravity holds them in place.

they have inertia. The concept of inertia states that "in the absence of external forces, a body in motion tends to remain in motion; a body at rest tends to remain at rest". Here, the beans were at rest and they will tend to remain at rest (remember the freely dropping banana cut by a knife example demonstrated during the first class).

A glass fiber can act as a pipe for light-light that enters the fiber at its end follows the fiber almost indefinitely without escaping through the fiber's surface. The light follows the fiber because electric charges in the glass attract the light and prevent it from accelerating outward, away from the center of the fiber. the fiber contains many tiny diverging lenses that focus the light back into the fiber over and over again. whenever it tries to leave the glass at a shallow angle, it's perfectly reflected. the fiber contains many tiny converging lenses that focus the light back into the fiber over and over again.

whenever it tries to leave the glass at a shallow angle, it's perfectly reflected. All the light rays trying to leave the glass fiber hits the surface with a shallow angle, therefore, they are reflected perfectly, i.e. total internal reflection, but not refracted so that they can successfully get out.

You remove the batteries from a working flashlight, turn both of them around as a pair, and reinsert them in the flashlight. They make good contact with the flashlight's terminals at both ends, so that there is no mechanical problem preventing the flashlight from working. If you now switch on the flashlight, it will not work because only electrons can actually move through a circuit. The positively charged atomic nuclei are immobile. work properly, although current will now be flowing backward through its circuit. not work because the batteries can't send current backward through the flashlight's circuit. not work because the light bulb can only carry electric current in one direction.

work properly, although current will now be flowing backward through its circuit Reversing the batteries as a pair merely reverses the direction in which the chain of batteries pumps charge. Current continues to flow through the circuit but in the opposite direction from before. This current still derives energy from the batteries and deposits it in the bulb's filament. The flashlight continues to work just fine.

A speedboat is pulling a water-skier with a rope, exerting a large forward force on her. The skier is traveling in a straight line at constant speed. The net force she experiences is both forward and backward. in the forward direction. in the backward direction. zero.

zero Constant speed means zero acceleration thus the net force will be zero as well.

A car battery is labeled as providing 12 V. Compare the electrostatic potential energy of positive charge on the battery's negative terminal with that on its positive terminal. A positive charge on the battery's positive terminal will have more electrostatic potential energy than on its negative terminal. A positive charge on the battery's positive terminal will have less electrostatic potential energy than on its negative terminal. A positive charge on the battery's positive terminal will have the same electrostatic potential energy as on its negative terminal. A positive charge on either terminal will have no electrostatic potential energy.

A positive charge on the battery's positive terminal will have more electrostatic potential energy than on its negative terminal. In order to keep/bring a positive charge on the battery's positive terminal (including enormous amount of positive charges), a positive work has to be performed on the charge (since like charges will repel each other, you have to do a positive work to keep/bring a positive charge next to other positive charges) and this positive work is stored as the electrostatic potential energy. On the other hand, keeping/bringing a positive charge on the negative terminal is an easier thing to do therefore doesn't require too much work. As a result, we can say that the potential energy of the first case (positive charge is on the positive terminal) is more than the second case.

Why can't an audio amplifier operate without batteries or a power supply? To produce a more powerful copy of an input signal, the amplifier needs a source of energy. To produce a more powerful copy of an input signal, the amplifier needs a source of current. To produce a more powerful copy of an input signal, the amplifier needs a source of voltage. All of the above choices are correct.

All of the above choices are correct.

The magnetostatic forces between two button magnets decrease surprisingly quickly as their separation increases. Use Coulomb's law for magnetism and the dipole character of each button magnet to explain this effect. As separation distance increases, the distance separating the two pairs of poles is very large and therefore the attractive and repulsive forces nearly cancel. The distance separating the two pairs of poles is always very small and therefore the attractive and repulsive forces always cancel. The distance separating the two pairs of poles is always very large and therefore the attractive and repulsive forces always cancel. As separation distance increases, the distance separating the two pairs of poles is very small and therefore the attractive and repulsive forces nearly cancel.

As separation distance increases, the distance separating the two pairs of poles is very small and therefore the attractive and repulsive forces nearly cancel. When the two button magnets are far apart, there is almost no difference between the distances separating their two pairs of poles. Two of the pairings are repulsive (north-north and south-south) and two pairings are attractive (north-south and south-north) and since the distances in those pairings are nearly identical the repulsive and attractive forces nearly cancel. But when the two button magnets approach one another closely, the various distances are no longer so similar. One of the pairings is likely to become dominant as the distance separating that pairing of poles because relatively small compared to the distance separating the other pairings. If the closely spaced poles are opposite, the overall forces on the buttons will be attractive. If the poles are like, the overall forces will be repulsive.

One type of microphone has a permanent magnet and a coil of wire that move relative to one another in response to sound waves. Why is the current in the coil related to the motion? As the coil moves through the magnetic field, electric charges are created in the coil and experience forces and thus flow through the coil as current that is proportional to the coil's velocity through the magnetic field. As the coil moves through the magnetic field, electric charges are created in the coil and experience forces and thus flow through the coil as current that is inversely proportional to the coil's velocity through the magnetic field. As the coil moves through the magnetic field, electric charges in the coil experience forces and thus flow through the coil as current that is inversely proportional to the coil's velocity through the magnetic field. As the coil moves through the magnetic field, electric charges in the coil experience forces and thus flow through the coil as current that is proportional to the coil's velocity through the magnetic field.

As the coil moves through the magnetic field, electric charges in the coil experience forces and thus flow through the coil as current that is proportional to the coil's velocity through the magnetic field. Reversing the batteries as a pair merely reverses the direction in which the chain of batteries pumps charge. Current continues to flow through the circuit but in the opposite direction from before. This current still derives energy from the batteries and deposits it in the bulb's filament. The flashlight continues to work just fine.

If most of the highest energy valence levels in a diode laser's p-type anode weren't empty, it would become relatively inefficient and probably wouldn't emit laser light at all. Why not? Electrons in the highest valence levels can reflect the laser light while undergoing radiative transitions to the conduction levels and that reflection would trap the laser radiation and reduce the diode's ability to emit laser light. Electrons in the highest conduction levels can absorb the laser light while undergoing radiative transitions to the valence levels and that absorption would trap the laser radiation and reduce the diode's ability to emit laser light. Electrons in the highest conduction levels can reflect the laser light while undergoing radiative transitions to the valence levels and that reflection would trap the laser radiation and reduce the diode's ability to emit laser light. Electrons in the highest valence levels can absorb the laser light while undergoing radiative transitions to the conduction levels and that absorption would trap the laser radiation and reduce the diode's ability to emit laser light.

Electrons in the highest valence levels can absorb the laser light while undergoing radiative transitions to the conduction levels and that absorption would trap the laser radiation and reduce the diode's ability to emit laser light. The diode laser needs a substantial population inversion to operate well. Electrons in the highest valence levels can absorb the laser light while undergoing radiative transitions to the conduction levels. That absorption would trap the laser radiation and reduce the diode's ability to emit laser light.

If the low-pressure neon vapor in a neon sign were replaced by a low-pressure mercury vapor, the sign would emit almost no visible light. Why not? Excited mercury atoms emit primarily invisible infrared light. Excited mercury atoms emit primarily invisible white light. Excited mercury atoms do not emit any type of light. Excited mercury atoms emit primarily invisible ultraviolet light.

Excited mercury atoms emit primarily invisible ultraviolet light Mercury has its resonance line in the ultraviolet. Our eyes are only sensitive to light in a well defined energyi/wavelegth range. Electromagnetic waves in the ultraviolet spectrum have too short of wavelength to be detected by our eyes.

The Empire State Building has several FM antennas on top, added in part to increase its overall height. These antennas aren't very tall. Why do short antennas, located high in the air, do such a good job of transmitting FM radio? FM radio transmission involves high-frequency, short-wavelength radio waves and since a good antenna is one-quarter wavelength long, FM radio transmission requires relatively short antennas. FM radio transmission involves low-frequency, long-wavelength radio waves and since a good antenna is one wavelength long, FM radio transmission requires relatively short antennas. FM radio transmission involves low-frequency, long-wavelength radio waves and since a good antenna is one-quarter wavelength long, FM radio transmission requires relatively short antennas. FM radio transmission involves high-frequency, short-wavelength radio waves and since a good antenna is one wavelength long, FM radio transmission requires relatively short antennas.

FM radio transmission involves high-frequency, short-wavelength radio waves and since a good antenna is one-quarter wavelength long, FM radio transmission requires relatively short antennas. First of all, the wavelength of a typical FM radio wave is about 1 meter (just an arbitrary length within the range). Also, it is known that a length of a good transmitting antenna is equal to one-quarter wavelength. Therefore, the size of the transmitting antenna should be about 25 cm (equivalent to 10 inch).

The neighborhood joker comes up to you and is really on a roll this morning. After several "good ones" they then say "OK so you're taking physics, right? Here's one - if the acceleration of gravity is 9.8 m/s2 then why isn't everything accelerating? HAHAHA". Being a dedicated student you give this question some real thought and come up with a reasonable response. You might say Gravity acts only on things that are not touching a surface. Gravity is just part of the story and it is the total net external force that determines acceleration. Most objects have too much inertia for us to see them accelerate under the influence of gravity. All things really do accelerate but we accelerate with them so we can't tell.

Gravity is just part of the story and it is the total net external force that determines acceleration The answer is very obvious. However, let me give a supporting example. Assume that you are on a surface. There is the gravity acting on you in downward direction, however, there is also a normal force (the force acting on you due to the ground) that is equal to your weight in magnitude but in upward direction thus there is zero net force (which means no acceleration HAHAHA!).

Diamond has an index of refraction of 2.42. If you put a diamond in water, you see reflections from its surfaces. However, if you put it in a liquid with an index of refraction of 2.42, the diamond is invisible. Why is it invisible, and how is this effect useful to a jeweler or gemologist? If the liquid and diamond have the same index of refraction, then light changes speed on entry to or exit from the diamond and no light reflects from the interface between the two. If the liquid and diamond have the same index of refraction, then light changes speed on entry to or exit from the diamond and all light reflects from the interface between the two. If the liquid and diamond have the same index of refraction, then light doesn't change speed on entry to or exit from the diamond and no light reflects from the interface between the two. If the liquid and diamond have the same index of refraction, then light doesn't change speed on entry to or exit from the diamond and all light reflects from the interface between the two.

If the liquid and diamond have the same index of refraction, then light doesn't change speed on entry to or exit from the diamond and no light reflects from the interface between the two. Reflection occurs when the speed of light changes in materials. If the speed does not change, there will be no reflection. The reflection occurs because the electric part of the wave loses energy as it accelerates charges in the material, while the magnetic part of the wave is unaffected. However, a electromagnetic wave must have a balance between the electric and magnetic parts of wave. As a consequence, the magnetic part loses a comparable amount of energy causing some of the light to reflect.

Why doesn't increasing the current passing through an LED affect the color of its light? Increasing the current will result in a brighter LED but the color of light produced by the LED is determined primarily by the anode's band gap in the LED's semiconductor. Increasing the current will result in a brighter LED but the color of light produced by the LED is determined primarily by the cathode's band gap in the LED's semiconductor. Increasing the current will result in a dimmer LED but the color of light produced by the LED is determined primarily by the cathode's band gap in the LED's semiconductor. Increasing the current will result in a dimmer LED but the color of light produced by the LED is determined primarily by the anode's band gap in the LED's semiconductor.

Increasing the current will result in a brighter LED but the color of light produced by the LED is determined primarily by the anode's band gap in the LED's semiconductor. The color of light emitted by an LED depends primarily on the band gap in the LED's semiconductor. The level differences corresponds to a particular energy difference, which is emitted as a photon with a particular energy, frequency (and color).

When the brakes on his truck fail, the driver steers it up a runaway truck ramp. As the truck rolls up the ramp, it slows to a stop. What happens to the truck's kinetic energy, its energy of motion? It is lost. It turns into heat. It converts into gravitational potential energy. It turns into friction.

It converts into gravitational potential energy. As the truck rolls up the ramp, it gains the gravitational potential energy which comes from the kinetic energy that the truck has due to its velocity (please note that the kinetic energy decreases in time and will be equal to zero when the truck reaches to its maximum height where the velocity will be zero)

Suppose you have a car traveling down the road at constant speed and not changing direction. It is experiencing gravity, wind resistance and frictional forces from the road. What can be said about the car's acceleration? It is not accelerating because it has constant velocity. It is accelerating because there are forces acting on it. It is not accelerating because gravity holds it down. It accelerating because the motor is running, propelling the car forward.

It is not accelerating because it has constant velocity. Although thee are all these forces (gravity, wind resistance and friction) acting on the car, the overall velocity is still constant which means no acceleration.

On a rainy day you can often see oil films on the surfaces of puddles. Why do these films appear brightly colored? Light reflects from the top and bottom surfaces of an oil film and the two reflections interfere with one another and the type of interference, constructive or destructive, depends only on the film's thickness. Light reflects from the top and bottom surfaces of an oil film and the two reflections interfere with one another and the type of interference, constructive or destructive, depends only on the light's wavelength. Light reflects from the top and bottom surfaces of an oil film and the two reflections interfere with one another and the type of interference, constructive or destructive, is independent of the film's thickness as well as the light's wavelength. Light reflects from the top and bottom surfaces of an oil film and the two reflections interfere with one another and the type of interference, constructive or destructive, depends on the film's thickness as well as the light's wavelength.

Light reflects from the top and bottom surfaces of an oil film and the two reflections interfere with one another and the type of interference, constructive or destructive, depends on the film's thickness as well as the light's wavelength. The colored occur because of the phenomenon of interference. The light rays reflected from top surface and the light rays reflected from the bottom surface both travel toward the observer and overlap. Both of these light rays are made of electromagnetic waves, so they have electric fields that vary sinusoidally. If the sine waves are "in step" (or more technically, in phase) with one another, the two rays interfere constructively, and the intensity of the light is large. If the sine waves are "out of step" (or out of phase) with one another, the two rays interfere destructively and the intensity of the light is small. Whether they are in step or out of step with one another is determined by the exact distance between the two surfaces. It tends to be the case that the waves are only "in step" for certain colors at a time, hence your see different colors in different regions.

Use the concepts of refraction, reflection, and dispersion to explain why a diamond emits a spray of colored lights when sunlight passes through its cut facets. Light refracts as it enters the diamond, reflects from the back surface, and refracts and disperses as it exits the diamond. Light refracts and disperses as it enters the diamond, reflects from the back surface, and refracts and disperses as it exits the diamond. Light refracts as it enters the diamond, reflects from the back surface, and disperses as it exits the diamond. Light disperses as it enters the diamond, reflects from the back surface, and refracts as it exits the diamond.

Light refracts and disperses as it enters the diamond, reflects from the back surface, and refracts and disperses as it exits the diamond Light bends and disperses on entry, reflects from the back surface, and bends and disperses more on exit from the diamond.

Dish-shaped reflectors are used to steer microwaves in order to establish communications links between nearby buildings. Those reflectors are often made from metal mesh. Why don't they have to be made from solid metal sheets? Microwaves will not respond to holes in the metal that are significantly smaller than their wavelengths. Microwaves will not respond to holes in the metal that are significantly larger than their wavelengths. Microwaves will not respond to holes in the metal that are equal to their wavelengths. None of the above choices are correct.

Microwaves will not respond to holes in the metal that are significantly smaller than their wavelengths. The holes in the solid metal sheet are smaller than the wavelength of microwaves, therefore, the metal mesh with bigger holes is preferred to use in the production of dish-shaped reflectors. The metal mesh is equivalent to solid metal as far as the microwaves are concerned.

When two medium-sized nuclei are stuck together during an experiment at a nuclear physics lab, the result is usually a large nucleus with too few neutrons to be stable. The nucleus soon falls apart. Why could more neutrons make it stable? Neutrons would experience the attractive nuclear force while diluting the repulsion between electrons. Neutrons would experience the attractive gravitational force while diluting the repulsion between protons. Neutrons would experience the attractive gravitational force while diluting the repulsion between electrons. Neutrons would experience the attractive nuclear force while diluting the repulsion between protons.

Neutrons would experience the attractive nuclear force while diluting the repulsion between protons.

A typical bar magnet has an "N" stamped on its north pole end and an "S" stamped on its south pole end. With the right tools, you might be able to change this bar magnet in one or more of the following ways: (1) remove its magnetic poles altogether, (2) reverse its magnetic poles so that it has a north pole at the end stamped "S" and a south pole at the end stamped "N", (3) convert its north pole into a south pole so that it has south poles at both ends and no north poles. Which of those three options is physically possible? Only (2) and (3) All three are possible. Only (1) and (2) None of them is possible.

Only (1) and (2) While it is possible to demagnetize a permanent magnet, by randomizing the magnetic orientations of its microscopic magnetic domains, or remagnetize a permanent magnet backwards, by exposing it to a strong, reversed magnetic field, you can't get give it a net magnetic pole. Putting south pole at both ends of the magnet would leave it with a net south magnetic pole and that's not possible. No free magnetic pole has ever been found in nature, so north and south poles always appear in equal pairs.

If you're wearing polarizing sunglasses and want to see who else is wearing polarizing sunglasses, you only have to turn your head sideways and look to see which people now have sunglasses that appear completely opaque. Why does this test work? Polarizing sunglasses normally block vertically polarized light, so when you look at someone's eyes when they are wearing polarizing sunglasses, you see only horizontally polarized light. Tilting your head sideways will allow your sunglasses to block vertically polarized light and thus you will see no light coming from the eyes of other people wearing polarizing sunglasses. Polarizing sunglasses normally block vertically polarized light, so when you look at someone's eyes when they are wearing polarizing sunglasses, you see only vertically polarized light. Tilting your head sideways will allow your sunglasses to block vertically polarized light and thus you will see no light coming from the eyes of other people wearing polarizing sunglasses. Polarizing sunglasses normally block horizontally polarized light, so when you look at someone's eyes when they are wearing polarizing sunglasses, you see only vertically polarized light. Tilting your head sideways will allow your sunglasses to block vertically polarized light and thus you will see no light coming from the eyes of other people wearing polarizing sunglasses. Polarizing sunglasses normally block horizontally polarized light, so when you look at someone's eyes when they are wearing polarizing sunglasses, you see only horizontally polarized light. Tilting your head sideways will allow your sunglasses to block vertically polarized light and thus you will see no light coming from the eyes of other people wearing polarizing sunglasses.

Polarizing sunglasses normally block horizontally polarized light, so when you look at someone's eyes when they are wearing polarizing sunglasses, you see only vertically polarized light. Tilting your head sideways will allow your sunglasses to block vertically polarized light and thus you will see no light coming from the eyes of other people wearing polarizing sunglasses. Polarizing sunglasses normally block horizontally polarized light, so when you look at someone's eyes when they are wearing polarizing sunglasses, you see only vertically polarized light. If you wear polarizing sunglasses and tip your head sideways, then your sunglasses will block vertically polarized light. You will see no light coming from the eyes of other people wearing polarizing sunglasses.

Holding your hand on a static generator (e.g., a Van de Graff generator) can make your hair stand up, but only if you are standing on a good electrical insulator. Why is that insulator important? Standing on an insulator or a conductor will have the same end results. Standing on a conductor would be better than an insulator since charges flow readily through a conductor. Standing on an insulator allows you to retain the charges transferred from the static generator. Standing on an insulator prevents you from retaining the charges transferred from the static generator.

Standing on an insulator allows you to retain the charges transferred from the static generator. If you are not on a good insulator, all the charges that are transferred on you from the Van De Generator's surface will go to the ground and you will only act like a piece of wire (without having a big net charge) between the Van de Graff machine and ground.

An acorn falls from a branch located 9.8 m above the ground. After 1 s of falling, the acorn's velocity will be 9.8 m/s downward. Why hasn't the acorn hit the ground? The gravity is weaker farther from the earth, so it wasn't going fast enough when it started falling. Air resistance held it back. This is incorrect. The acorn has hit the ground after 1 s of fall. The acorn's average speed for the 1 s is less than 9.8 m/s.

The acorn's average speed for the 1 s is less than 9.8 m/s. Although the speed of the acorn is 9.8 m/s after a second, the average speed in that second will be less than 9.8 since acorn started its motion from zero speed. Therefore, it is not possible for the acorn to take 9.8 m distance in 1 sec.

If you bring a button magnet near an iron pipe, they will soon begin attracting one another. Why don't they repel? The button magnet's magnetic field causes positive ions to move to one side of the pipe and negative ions to move to the other side of the pipe and thus attracts the magnet. The button magnet's magnetic field polarizes the iron pipe and the pipe develops an opposite pole near the approaching pole of the button magnet and thus attracts the magnet. The button magnet's magnetic field polarizes the iron pipe and the pipe develops a like pole near the approaching pole of the button magnet and thus attracts the magnet. The iron pipe is not magnetic so the button magnet would never be attracted or repelled by the iron pipe.

The button magnet's magnetic field polarizes the iron pipe and the pipe develops an opposite pole near the approaching pole of the button magnet and thus attracts the magnet. Since there is an opposite pole is developed in iron, the force will be attractive but not repulsive (remember: opposite poles attract, like poles repel).

The electric field around an electrically charged hairbrush diminishes with distance from the hairbrush. Use Coulomb's law to explain this decrease in the magnitude of the field. The electrostatic forces between the hairbrush and a positive charge diminish with decreasing separation distance which results in a smaller electric field. The electrostatic forces between the hairbrush and a positive charge grow with decreasing separation distance which results in a smaller electric field. The electrostatic forces between the hairbrush and a positive charge grow with increasing separation distance which results in a smaller electric field. The electrostatic forces between the hairbrush and a positive charge diminish with increasing separation distance which results in a smaller electric field.

The electrostatic forces between the hairbrush and a positive charge diminish with increasing separation distance which results in a smaller electric field. According to Coulomb's law, the electrostatic force is inversely proportional to distance's square. Thus, the elec. force diminishes as the distance becomes larger. And a small electrostatic force acting on a charged particle means the particle is in a weak electric field that is created by other charges.

A Ping-Pong ball contains an enormous number of electrically charged particles. Why don't two Ping-Pong balls normally exert electrostatic forces on each other? Their mass is too small to exert electrostatic forces. The electrostatic forces cancel due to like net charges on each ball. The electrostatic forces cancel due to zero net charges on each ball. The electrostatic forces cancel due to opposite net charges on each ball.

The electrostatic forces cancel due to zero net charges on each ball First, having enormous number of electrically charged particles doesn't mean that balls have a net charge. If there are two ping-pong balls with no net charge (although this is not very clearly said in the question) staying/kept next to each other, there will be no electrostatic force between them. (Alternatively, you can say that the individual electrostatic forces between the charges on two ping-pong balls will cancel out when you add them up and we will get no net electrostatic force)

The gate of a MOSFET is separated from the channel by a fantastically thin insulating layer. This layer is easily punctured by static electricity, yet the manufacturers continue to use thin layers. Why would thickening the insulating layer spoil the MOFSET's ability to respond to charge on its gate? The gate's charge must be very near the channel in order to attract like charges and draw the charge into the channel. The gate's charge must be very near the channel in order to attract opposite charges and draw the charge into the channel . The gate's charge must be very far from the channel in order to attract opposite charges and draw the charge into the channel. The gate's charge must be very far from the channel in order to attract like charges and draw the charge into the channel.

The gate's charge must be very near the channel in order to attract opposite charges and draw the charge into the channel.

If you hold your camera up to a small hole in a fence, you will be able to take a picture of the scene on the other side. However, the exposure time will have to be quite long, and the depth of focus will be surprisingly large. Explain. The hole effectively reduces the diameter of the camera lens and small diameter lenses have large depths of focus because many light rays manage to get through the small opening and are already close to one another but they require longer exposures because so little light passes through the narrow lens opening. The hole effectively reduces the diameter of the camera lens and small diameter lenses have large depths of focus because the few light rays that manage to get through the small opening are already close to one another but they require longer exposures because more light passes through the narrow lens opening. The hole effectively reduces the diameter of the camera lens and small diameter lenses have large depths of focus because many light rays manage to get through the small opening and are already close to one another but they require longer exposures because more light passes through the narrow lens opening. The hole effectively reduces the diameter of the camera lens and small diameter lenses have large depths of focus because the few light rays that manage to get through the small opening are already close to one another but they require longer exposures because so little light passes through the narrow lens opening.

The hole effectively reduces the diameter of the camera lens and small diameter lenses have large depths of focus because the few light rays that manage to get through the small opening are already close to one another but they require longer exposures because so little light passes through the narrow lens opening. The hole effectively reduces the diameter of the camera lens. Small diameter lenses have large depths of focus (because those few light rays that manage to get through the small opening are already close together) but require longer exposures (because so little light passes through the narrow lens opening).

Increasing the power to an incandescent bulb makes its filament hotter and its light whiter. Why doesn't increasing the power to a neon sign change its color? The incandescent lamp is emitting thermal radiation with a roughly blackbody spectrum. The neon sign is not a thermal light source, so increasing the power simply dims its light but does not change its spectrum. The incandescent lamp is emitting thermal radiation with a roughly blackbody spectrum. The neon sign is not a thermal light source, so increasing the power simply does nothing to the brightness of its light as well as its spectrum. The incandescent lamp is emitting thermal radiation with a roughly blackbody spectrum. The neon sign is not a thermal light source, so increasing the power simply brightens its light but does not change its spectrum. The incandescent lamp is emitting thermal radiation with a roughly blackbody spectrum. The neon sign is also a thermal light source, so increasing the power simply brightens its light but has no effect on its spectrum.

The incandescent lamp is emitting thermal radiation with a roughly blackbody spectrum. The neon sign is not a thermal light source, so increasing the power simply brightens its light but does not change its spectrum. Indancescent bulbs produce light as a result of their eight, as does the sun. As it gets hotter, the distribution shits toward the higher frequency blue/violet light. In contract, the light from a neon sign come from atomic transitions bewtween different orbitals (possible standing waves within neon). Only certain standing waves fit in Neon, and the spectrum is a fingeprint. Increasing power does not change this fingerprint.

A CD player uses a beam of laser light to read the disc, focusing that light to a spot less that 1 µm (10-6 m) in diameter. Why can't the player use a cheap incandescent lightbulb for this task, rather than a more expensive laser? The incandescent lightbulb's photons are all different and therefore will not focus to the same tiny spot. The incandescent lightbulb's photons are all the same and therefore will not focus to the same tiny spot. The incandescent lightbulb will not emit photons and thus will not focus to any spot. None of the above choices are correct.

The incandescent lightbulb's photons are all different and therefore will not focus to the same tiny spot The light from an incadenscent light bulb comes from the acceleration of individual charges (due to heat), and therefore are all independent (different directions frequencies), comprises of many individual waves. In contrast, laser light is coherent, same direction and wavelenght, i.e. one giant wave.

When you look into the front of a square glass vase filled with water, its sides appear to be mirrored. Why do the sides appear so shiny? The light that you are seeing is experiencing interference. The light that you are seeing is experiencing refraction. The light that you are seeing is experiencing diffraction. The light that you are seeing is experiencing total internal reflection

The light that you are seeing is experiencing total internal reflection You are seeing light that has experienced total internal reflection. That light tried to escape from the glass at too shallow an angle and reflected back into the glass instead.

If you hold a permanent magnet the wrong way in an extremely strong magnetic field, its magnetization will be permanently reversed. What happens to the magnetic domains inside the permanent magnet during this process? The magnetic domains of the permanent magnet that are aligned with the applied magnetic field grow while the domains opposite to the applied magnetic field shrink. The magnetic domains of the permanent magnet that are aligned with the applied magnetic field shrink while the domains opposite to the applied magnetic field grow. The magnetic domains of the permanent magnet that are aligned with the applied magnetic field as well as the domains that are opposite to the applied magnetic field will remain unchanged. The atoms of the permanent magnet move throughout the magnet until it is permanently reversed.

The magnetic domains of the permanent magnet that are aligned with the applied magnetic field grow while the domains opposite to the applied magnetic field shrink. Due to the extremely strong magnetic field (in which we hold a permanent magnet the wrong/opposite way on purpose), the magnetic domains of the permanent magnet that are aligned with the applied field will grow (because the strong mag. field forces magnetic dipoles in the permanent magnet to align with itself) while the domains that are opposite to the field will shrink.

A discharge in a mixture of gases is more likely to emit a full white spectrum of light than a discharge in a single gas. Why? The variety of possible radiative transitions is independent of the mixture of gases and thus, the spectrum of light emitted will be identical to a discharge in a single gas. It depends on the mixture of gases. The more different atoms and molecules present in a mixture of gases, the less variety there is in the possible radiative transitions and thus, the more likely that a full spectrum of white light will be emitted by the discharge. The more different atoms and molecules present in a mixture of gases, the more variety there is in the possible radiative transitions and thus, the more likely that a full spectrum of white light will be emitted by the discharge.

The more different atoms and molecules present in a mixture of gases, the more variety there is in the possible radiative transitions and thus, the more likely that a full spectrum of white light will be emitted by the discharge. When an appropriate spectrum of red, green, and blue light reach our eyes we see white light.

If you connect the output of one inverter to the input of a second inverter, how will the output of the second inverter be related to the input of the first inverter? The output of the second inverter will have no bit. The output of the second inverter will be the same as the input to the first inverter. The output of the second inverter will be the same as the output of the first inverter. The output of the second inverter will be the same as the input to the second inverter.

The output of the second inverter will be the same as the input to the first inverter.

Although a particular AM radio station claims to transmit 50,000 W of music power, that's actually its average power. There are times when it transmits more power than that and times when it transmits less. Explain. The power being transmitted is changed in order to represent air pressure fluctuations with the radio wave: compressions are represented by strengthening the radio wave and rarefactions are represented by weakening the radio wave. The power being transmitted is changed in order to represent air pressure fluctuations with the radio wave: compressions are represented by weakening the radio wave and rarefactions are represented by strengthening the radio wave. The power being transmitted is changed in order to represent air pressure fluctuations with the radio wave: both compressions and rarefactions are represented by weakening the radio wave. The power being transmitted is changed in order to represent air pressure fluctuations with the radio wave: both compressions and rarefactions are represented by strengthening the radio wave.

The power being transmitted is changed in order to represent air pressure fluctuations with the radio wave: compressions are represented by strengthening the radio wave and rarefactions are represented by weakening the radio wave. More charges are accelerated in the antenna to represent high pressure and fewer charges to represent low pressure. These result and stronger and weaker amplitude radio waves.

Why can light from a blue laser form a narrower beam waist than light from an infrared laser? The size of the beam waist depends largely on the wavelength of the light and since blue light has a shorter wavelength than infrared light, blue light can form a narrow beam waist. The size of the beam waist depends largely on the frequency of the light and since blue light has a smaller frequency than infrared light, blue light can form a narrow beam waist. The size of the beam waist depends largely on the energy of the light and since blue light has less energy than infrared light, blue light can form a narrow beam waist. All of the above choices are correct.

The size of the beam waist depends largely on the wavelength of the light and since blue light has a shorter wavelength than infrared light, blue light can form a narrow beam waist. The size of the beam waist depends in large measure on the wavelength of the light, with the beam waist limited to a diameter of roughly that wavelength. Since blue light has a shorter wavelength (405nm) than infrared light (800nm), blue light can form a narrow beam waist.

Why is it difficult or impossible to make very small atomic bombs? The smaller the nuclear fuel component, the more likely it is that a neutron will escape before it causes a fission and the less efficient the fuel is at using fission neutrons to sustain a chain reaction. The smaller the nuclear fuel component, the more likely it is that an electron will escape before it causes a fission and the less efficient the fuel is at using fission neutrons to sustain a chain reaction. The smaller the nuclear fuel component, the more likely it is that a neutron will escape before it causes a fission and the less efficient the fuel is at using fission electrons to sustain a chain reaction. The smaller the nuclear fuel component, the more likely it is that an electron will escape before it causes a fission and the less efficient the fuel is at using fission electrons to sustain a chain reaction.

The smaller the nuclear fuel component, the more likely it is that a neutron will escape before it causes a fission and the less efficient the fuel is at using fission neutrons to sustain a chain reaction.

When a sodium atom is in its lowest energy excited state, it can emit light. Why? The sodium atom can undergo a radiative transition to its ground state, thereby emitting a photon of light. The sodium atom can never emit a photon of light. The sodium atom can undergo a radiative transition to a higher energy excited state, thereby emitting a photon of light. None of the above choices are correct.

The sodium atom can undergo a radiative transition to its ground state, thereby emitting a photon of light. The sodium atom can undergo a radiative transition to its ground state, thereby emitting a photon of (yellow) light. If it were instead in its ground state (not excited state/natural state/stable state), there wojuld no way the most outer electron of this atom can go to a lower state (because it is already in the ground state) and no light would be emitted.

In an n-channel MOSFET, the source and drain are connected by a thin strip of p-type semiconductor. Why is this device labeled as having an n-channel rather than a p-channel? The strip of p-type semiconductor becomes effectively n-type when extra electrons are drawn away from it by nearby positive charge on its gate. The strip of p-type semiconductor becomes effectively n-type when extra electrons are drawn into it by nearby negative charge on its gate. The strip of p-type semiconductor becomes effectively n-type when extra electrons are drawn into it by nearby positive charge on its gate. The strip of p-type semiconductor becomes effectively n-type when extra electrons are drawn away from it by nearby negative charge on its gate.

The strip of p-type semiconductor becomes effectively n-type when extra electrons are drawn into it by nearby positive charge on its gate.