PHYS 1600 Final
A diode containing a pn-junction will conduct electric current only if the depletion region near the junction is (A) eliminated by pushing electrons onto the n-type side and removing them from the p-type side. (B) enlarged by pushing electrons onto the n-type side and removing them from the p-type side. (C) eliminated by pushing electrons onto the p-type side and removing them from the n-type side. (D) enlarged by pushing electrons onto the p-type side and removing them from the n-type side.
A
After a narrow laser beam passes through a converging lens, its diameter decreases to (A) a minimum value that is proportional to the wavelength of the light and then starts increasing. (B) a minimum value that is proportional to the intensity of the light and then starts increasing. (C) a minimum value that is proportional to the frequency of the light and then starts increasing. (D) zero and then starts increasing.
A
An LED (a light-emitting diode) emits light when an electron that has crossed the pn-junction from the (A) n-type side to the p-type side drops from a conduction band level to a valence band level. (B) p-type side to the n-type side jumps from a valence band level to a conduction band level. (C) p-type side to the n-type side drops from a conduction band level to a valence band level. (D) n-type side to the p-type side jumps from a valence band level to a conduction band level.
A
An electric motor is turning the belt of a treadmill. Before you get on the treadmill, the motor is consuming a certain amount of electric power to keep the belt moving. You get on the treadmill and it tilts so that you are effectively running uphill. Your feet are pulling the belt downhill and the motor now acts to keep the belt from turning too fast. The motor is now (A) generating electric power. (B) consuming more electric power than before. (C) consuming the same amount of electric power as before. (D) consuming less electric power than before.
A
An engineer is installing a radio antenna for a new music station. The frequency of that station's radio wave is 100 MHz and its wavelength is 3.00 meters. The antenna projects upward from the top of a metal building. To be as effective as possible at emitting the radio wave, how tall should that antenna be? (A) 0.75 meters tall. (B) It should be as tall as possible, but it must be completely rigid so that it doesn't bend the radio wave. (C) 3.00 meters tall. (D) 1.50 meters tall.
A
Compared to a red LED (light-emitting diode), a blue LED (A) contains a semiconductor with a larger band gap (energy gap) between its valence band and its conduction band. (B) operates at a lower temperature and therefore emits bluer light. (C) operates at a higher temperature and therefore emits bluer light. (D) contains a semiconductor with a smaller band gap (energy gap) between its valence band and its conduction band.
A
Compared to an ordinary AA battery, an ordinary D battery (A) has the same voltage but can supply more total electrical energy. (B) has a higher voltage but can supply the same total electrical energy. (C) has a higher voltage and can supply more total electrical energy. (D) has the same voltage and can supply the same total electrical energy.
A
During a particular brown out, the voltage of the electrical power provided to your home by the power company is reduced by 5%. The voltage drop across your reading lamp is reduced by 5% so the current passing through it is also reduced by 5%. Overall, the power consumed by the lamp (A) drops by about 10%. (B) drops by about 25%. (C) remains the same but the lamp becomes dimmer. (D) drops by about 5%.
A
It's a rainy day at the gasoline station and you see a puddle that has a thin film of gasoline floating on its surface. The reflection of a white cloud in that puddle appears red because (A) the partial reflections from the top and bottom surfaces of the gasoline film interfere constructively at your eye only for the red portion of the spectrum. (B) red light reflects more strongly as it enters the gasoline film than other colors of light do. (C) gasoline is red in color and it absorbs red light. (D) red light bends more strongly as it enters the gasoline film than other colors of light do.
A
The electrons in an atom reside in orbitals. Those orbitals are best described as (A) standing waves that extend around the atom's nucleus but do not change with time. (B) circular orbits in which the planet-like electrons loop around the atom's nucleus. (C) elliptical orbits in which the planet-like electrons loop around the atom's nucleus. (D) parabolic orbits in which the planet-like electrons loop around the atom's nucleus.
A
When a uranium nucleus undergoes fission, it releases an enormous amount of energy. Before the fission, that energy was stored as (A) electrostatic potential energy (energy stored in electrostatic forces). (B) nuclear potential energy (energy stored in nuclear forces). (C) magnetic potential energy (energy stored in magnetostatic forces). (D) pressure potential energy (energy stored in pressure forces).
A
When the pressure of the gas inside a sodium-vapor or mercury-vapor discharge lamp increases from low-pressure to high-pressure, that lamp's light spectrum changes remarkable. Compared to its low-pressure spectrum, the lamp's high-pressure spectrum (A) includes a much wider range of wavelengths due to collisions and is almost dark at its "resonance line" due to radiation trapping. (B) is much dimmer because the high pressure causes most of the electrical energy to be converted into thermal energy. (C) includes far fewer wavelengths because collisions limit the colors of light the gas atoms can emit. (D) includes a much wider range of wavelengths due to the higher gas temperature inside the lamp.
A
You accidentally leave a thick metal spoon in a glass bowl of soup that you put in the middle of a microwave oven. When you turn on the microwave oven, (A) nothing unusual happens because the spoon is a good electrical conductor and has smooth ends. (B) the spoon becomes radioactive, so that it should be discarded where no one will come into contact with it. (C) the spoon becomes extremely hot and scorches the soup in only a few second. (D) sparks shoot out of the spoon toward the top of the oven's cooking chamber.
A
You and your friends are riding skateboards down a hill. There are two paths from the top of the hill to the bottom: both are smooth ramps, but one is twice as long as the other. You take the short ramp and your friend takes the long ramp. Neglecting friction and air resistance, (A) you accelerate twice as quickly as your friend, but your speeds are the same at the bottom of the hill. (B) you and your friend accelerate equally, but when you are both at the bottom of the hill, your speed is greater than your friend's speed. (C) you accelerate slightly less than twice as quickly as your friend, but your speeds are the same at the bottom of the hill. (D) you accelerate slightly less than twice as quickly as your friend, but when you are both at the bottom of the hill, your speed is greater than your friend's speed.
A
You are jumping on a trampoline. You sometimes you do work on the trampoline and sometimes it does work on you. The time when you do work on the trampoline is (A) when you are touching its surface and that surface is moving downward. (B) when you are touching its surface and that surface is moving upward. (C) whenever you are touching its surface. (D) during the second half of the trampoline's movement downward and the first half of the trampoline's movement upward.
A
While a light wave from a distant star is traveling through empty space on its way to the earth, that light wave consists of (A) an electric charge and a magnetic field. (B) an electric charge and a magnetic pole. (C) an electric field and a magnetic pole. (D) an electric field and a magnetic field.
Answer: (D) an electric field and a magnetic field.
A bar magnet has a north pole at one end and a south pole at the other end. The north-pole end is painted red and the south-pole end is painted white. You cut the magnet in half, exactly between its red and white ends. The separated red end (A) has only a north pole. (B) has a north pole where it was originally and a south pole at the freshly cut end. (C) has only a south pole. (D) has two north poles, one where it was originally and another at the freshly cut end.
B
A capacitor consists of two conducting surfaces separated by an insulator. Suppose that those two conducting surfaces are both horizontal and that the top surface is positively charged while the bottom surface is negatively charged. The electric field in the insulator between those surfaces points (A) upward. (B) downward. (C) horizontally toward the left. (D) horizontally toward the right.
B
A microwave oven does a poor job of heating frozen food, but a good job of heating food that has already been defrosted. The reason for this difference is that (A) the microwaves magnetize the frozen food and become trapped, whereas they are unable to magnetize the defrosted food. (B) the water molecules in frozen food cannot rotate in response to the microwave's electric field, whereas the water molecules in defrosted food can rotate. (C) the electric charges in frozen food cannot move long distances, whereas the electric charges in defrosted food can move long distances. (D) the microwaves are frozen inside the frozen food and cannot cook it, whereas the microwaves travel easily in the defrosted food.
B
A typical laser oscillator has two mirrors, one at each end of the laser medium. These two mirrors (A) prevent heat from escaping from those ends so that the laser oscillator remains hot enough to emit brilliant laser light. (B) keep a few photons bouncing back and forth through the laser medium so that they can be duplicated over and over again. (C) prevent radio waves and microwaves from entering the laser medium, where they could overheat it. (D) prevent light from escaping from those ends so that it is only emitted through the front face of the laser oscillator.
B
For practical reasons, most AM radio stations have a single vertical transmitting antenna. If your radio used a single rod-shaped metal receiving antenna (which it does not do), you would receive the transmission best by orienting that receiving antenna so that it (A) is horizontal and points away from the transmitting antenna. (B) is vertical. (C) is horizontal and points at a right-angle to the line between you and the transmitting antenna. (D) is horizontal and points toward the transmitting antenna.
B
Of the following types of electromagnetic waves, the type with the highest frequency is (A) infrared light. (B) ultraviolet light. (C) microwaves. (D) visible light.
B
On a sunny day, you can use a circular magnifying glass to burn wood by focusing the sun's light to a small spot on the wood. Light from the sun reaches the magnifying glass, bends as it passes through the lens, and forms a small round, brilliant spot of light on the wood. The spot of light is round is because (A) particles of light (photons) are spherical and, when brought together at a focus, form a circular spot. (B) it is a real image of the round sun itself. The magnifying glass behaves like a camera lens. (C) a focus means that all light passing through the lens is brought together to a single point in space. A single point always looks round. (D) the magnifying glass is round. A square magnifying glass would create a square spot of light.
B
Running on soft dry sand is exhausting, so you switch to running on hard wet sand. The hard wet sand takes less energy from you because (A) it stops the downward motion of your foot faster and thus absorbs less of your momentum. (B) it doesn't move downward as you push downward on it, so you do almost zero work on it. (C) its water content gives it more mass and that prevents it from absorbing energy. (D) it pushes up on your foot just as hard as your foot pushes on it, unlike the soft dry sand.
B
The difference between a metal and an insulator lies in their band structures. An insulator is unable to conduct electric current in response to an electric field because (A) its band structure prevents its electrons from crossing the mid-point of the material without becoming positively charged. (B) all of its electrons reside in filled bands and thus can't shift into empty levels so as to move across the material. (C) its band structure prevents it from becoming electrically charged, as it must do in order to conduct current. (D) its band structure puts the guitars on the left and the drums on the right, so there is no room for the lead vocal.
B
Two billiard balls are rolling forward on a horizontal table, but the yellow ball is traveling twice as fast as the blue ball. The two balls roll off the edge of the table simultaneously. The yellow ball hits the ground (A) before the blue ball. (B) at the same time as the blue ball, but the yellow ball lands twice as far from the table as the blue ball. (C) after the blue ball. (D) at the same time as the blue ball, but the yellow ball lands four times as far from the table as the blue ball.
B
Two children of equal size and weight run along a horizontal platform side by side and dive into a swimming pool at exactly the same instant. The only difference between the two children's dives is that one child jumps upward off the platform while the other child simply runs forward off the end. You watch them fall and notice that (A) the two children reach the water at exactly the same instant. (B) the child who did not jump upward reaches the water first. (C) the child who jumped upward does not feel the pull of gravity and never returns. (D) the child who jumped upward reaches the water first.
B
When a piece of n-type semiconductor touches a piece of p-type semiconductor, a pn-junction forms. Following its formation, the region around that junction contains (A) an electric field and can conduct electric current. (B) an electric field and cannot conduct electric current. (C) no electric field and can conduct electric current. (D) no electric field and cannot conduct electric current.
B
When a technician adds a tiny amount of phosphorous to ultrapure silicon, the result is a material that has slightly more electrons than a perfect semiconductor should have. What happens to those electrons? (A) They reside in the material's valence band and they prevent this n-type material from conducting electric current. (B) They reside in the material's conduction band and they permit this n-type material to conduct electric current. (C) They reside in the material's valence band and they permit this n-type material to conduct electric current. (D) They reside in the material's conduction band and they prevent this n-type material from conducting electric current.
B
When electric current flows through a glass tube filled with low-pressure neon gas, that gas emits red light. The light is red because (A) a neon atom cannot store enough energy to emit any other color of light. (B) a neon atom's strongest radiative transition, its "resonance line," is in the red portion of the visible spectrum. (C) a neon atom stores too much energy to emit any other color of light. (D) neon naturally contains a red dye.
B
When you hold a strong permanent magnet near a piece of iron, that iron becomes magnetized. Iron is a ferromagnetic material and its intrinsic magnetism stems primarily from its (A) positrons. (B) electrons. (C) protons. (D) neutrons.
B
When you look in the front of a glass aquarium that is filled with water, the sides of that aquarium appear to be perfect mirrors. What is reflecting the light? [Note: Light travels slower in glass than in water and slower in water than in air.] (A) All of the light experiences total internal reflection from the boundary between the water and the glass. (B) A small fraction of the light reflects from the boundary between the water and the glass, but most of the light experiences total internal reflection from the boundary between the glass and the air. (C) All of the light experiences total internal reflection from the boundary between the glass and the air. (D) Most of the light experiences total internal reflection from the boundary between the water and the glass, but a small fraction of the light reflects from the boundary between the glass and the air.
B
When you toss your basketball onto a bookshelf, it bounces off the wall at the back of the shelf and soon falls to the floor. Getting the ball to stay on the shelf is almost impossible because the ball is unable to transfer (A) velocity to the wall or shelf. (B) energy to the wall or shelf. (C) momentum to the wall or shelf. (D) mass to the wall or shelf.
B
Which one of the following objects emits an electromagnetic wave that travels across the universe? (A) An electrically charged ball that is traveling at constant velocity inside a glass elevator. (B) An electrically charged ball that is going around in a circle at a constant speed on a plastic merry-go-round. (C) An electrically charged ball that is traveling at constant velocity on top of a metal truck. (D) An electrically charged ball that is motionless at the top of a tall metal building.
B
You are pulling a toy wagon filled with bricks and it is accelerating forward. If you are exerting a forward force of 30 newtons on the wagon's handle, the wagon's handle is exerting a backward force of (A) more than 30 newtons on your hand. (B) 30 newtons on your hand. (C) somewhat less than 30 newtons on your hand. (D) zero newtons on your hand.
B
You immerse a colorless glass marble in a bowl of colorless salad oil. Light travels at exactly the same speed in the glass marble as it does in the salad oil. While the marble is in the oil, (A) you see a real image formed by the marble. (B) you cannot see the marble at all. (C) you see a virtual image formed by the marble. (D) you see strong reflections from the marble surfaces.
B
You remove the glass carousel from a microwave oven and place a plate full of spaghetti on the bottom of the oven. After cooking the spaghetti for 2 minutes, you remove it from the oven and discover that it has been heated very unevenly. Some portions of the spaghetti are steaming hot while others are cold. What caused this uneven heating? (A) The glass carousel dish reflects the microwaves and focuses them on the food. Without that dish, the microwaves are blurry and cannot heat the food evenly. (B) Interference effects produced microwave intensities that varied from place to place in the oven. (C) The oven's microwaves flow out of a pipe on the right side of the oven and only heat food as it passes in front of that pipe. Without the rotating carousel, food that is near the pipe overheats while the rest of the food remains cold. (D) The glass carousel was needed to lift the spaghetti into the microwaves. Without it, only the top portion of the spaghetti was heated properly.
B
You walk to class at a steady pace along a flat, horizontal path. Your backpack weighs 100 newtons and your trip is 500 meters long. How much work do you do on your backpack? (A) 1/5 joule (1/5 newton-meters). (B) 0 joules (0 newton-meters). (C) 50,000 joules (50,000 newton-meters). (D) 5 joules (5 newton-meters).
B
You watch your friend ride upward in a glass elevator at constant velocity. He is holding a heavy package in his hands. From your inertial frame of reference on the ground at the base of the elevator, he is doing (A) zero work on the package because the package is stationary with respect to the elevator car. (B) positive work on the package. (C) negative work on the package. (D) zero work on the package because the package is stationary in his hands.
B
Your heirloom porcelain teacup has beautiful gold decorations on it, including a ring of gold that encircles the lip of the cup. If you heat the cup in a microwave oven, the gold ring will turn black in a few seconds because the microwaves will (A) magnetize the gold ring and cause it to attract black iron particles in the paint. (B) push currents back and forth through the gold ring, causing it to overheat and burn. (C) shift electrons between orbitals in the gold atoms and cause the gold atoms to emit black light. (D) interfere destructively inside the gold ring and shift its color from gold to black.
B
A gymnast doing a double back flip leaps off the floor with her arms and legs extended and then pulls herself into a very compact position. In her compact shape, she rotates very rapidly and completes two full rotations before opening back up to land on the floor. During the time that she is not touching the floor, the one aspect of her motion that is constant is her (A) velocity (B) angular velocity. (C) angular momentum. (D) momentum
C
A laser beam exhibits unusually strong interference effects because (A) its light is much hotter than light from other sources. (B) its light rays are more parallel to one another than light rays from other sources. (C) its light is coherent whereas light from other sources is incoherent. (D) its light is much brighter than light from other sources.
C
A rocking chair has damaged the cord of your desk lamp. One of the two wires in the cord is completely cut in half and cannot carry any current. However, the other wire still connects the lamp to the electric socket. If you switch on the lamp, (A) the normal amount of current will flow through the one remaining wire and the lamp will glow at half its normal brightness. (B) half the normal amount of current will flow through the one remaining wire and the lamp will glow at a quarter of its normal brightness. (C) no current will flow through either wire and the lamp will remain dark. (D) the normal amount of current will flow through both wires and the lamp will glow at its normal brightness.
C
A tank circuit consists of two simple components, a capacitor and an inductor. Tank circuits are useful in radio and many other electrical and electronic systems because they are (A) resonant devices for frequency: frequency moves back and forth in a tank circuit at a specific "resonant" wavelength. (B) amplifying devices: more electrical energy emerges from a tank circuit than enters that tank circuit. (C) resonant devices for electric charge: charge moves back and forth in a tank circuit at a specific "resonant" frequency. (D) amplifying devices: more electrical power emerges from a tank circuit than enters that tank circuit.
C
An optical communication fiber can carry light for miles with almost no loss of intensity. Light travels through the fiber's glass core and that core is coated with (A) a thin layer of pure aluminum. (B) a different glass that has a slower speed of light. (C) a different glass that has a faster speed of light. (D) a thin layer of pure silver.
C
If you carry positive charge from a region of high voltage to a region of low voltage, that charge will (A) become a smaller positive charge as a result of that move. (B) become negative charge as a result of that move. (C) do work on you during that move. (D) do negative work on you during that move.
C
If you hold a strong permanent magnet inside a metal ring and then yank the magnet out of the ring, you will create an electric field in the metal ring and an electric current will flow through that ring. If you do the same thing with a glass ring, no current will flow the ring because (A) removing the magnet from the glass ring does not create an electric field. (B) the glass ring creates its own magnetic field in the opposite direction and cancels out the electromagnetic effects. (C) although you will create an electric field in the glass ring, the ring has no mobile electric charges to carry an electric current. (D) the glass ring is made from a non-magnetic material. Since no magnetic fields can be present inside the ring, removing the magnet has no effect on the ring.
C
Increasing the diameter of your camera's lens, while leaving its focal length unchanged, will make the real image (A) dimmer and make focusing more critical by reducing the depth of focus. (B) brighter and make focusing less critical by increasing the depth of focus. (C) brighter and make focusing more critical by reducing the depth of focus. (D) dimmer and make focusing less critical by increasing the depth of focus.
C
The car you are driving skids off the road in bad weather and collides with a tree head on. Fortunately, the airbag inflates and protects your head from injury. By coming to a stop in the airbag instead of on the steering wheel, your head transferred (A) less momentum to the car and with a smaller force. (B) more momentum to the car but with a smaller force. (C) the same amount of momentum to the car but over a longer period of time and with a smaller force. (D) the same amount of momentum to the car in the same period of time but with a smaller force
C
The constituents of a radioactive nucleus are in stable equilibrium, yet they eventually rearrange in a way that allows the nucleus to fall apart and release stored energy. What allows the nucleus to escape from its stable equilibrium and subsequently fall apart? (A) The laws of electromagnetism. (B) The laws of motion. (C) The wave nature of matter (quantum physics). (D) The laws of thermodynamics.
C
The electrodes at the ends of a fluorescent lamp are heated red hot because (A) they will not burn out when the electrical discharge starts. (B) they must ignite the gas inside the tube so that the gas burns bright white. (C) they must release electrons into the gas inside the tube so that the gas becomes a plasma. (D) they must heat the gas inside the tube so that the gas glows bright white.
C
The microwave oven's cooking chamber has 6 sides. What are those sides made of? (A) 5 sides are metal and 1 side is plastic mesh. (B) 5 sides are plastic and 1 side is metal mesh. (C) 5 sides are metal and 1 side is metal mesh. (D) 5 sides are plastic and 1 side is plastic mesh.
C
The sky is blue because (A) the air contains atoms and molecules that absorb red, yellow, and green light, leaving only the blue light unaffected. (B) it contains atoms and molecules that emit blue light when they are exposed to cosmic rays. (C) tiny particles in the air scatter short wavelength light more effectively than they scatter long wavelength light. (D) tiny particles in the air scatter long wavelength light more effectively than they scatter short wavelength light.
C
The transformer in a power adapter has 120 turns in its primary coil and 10 turns in its secondary coil. With 120 volt AC power connected to the primary coil and a current of 1 ampere flowing through that primary coil, the transformer's secondary coil is supplying (A) 12 volt AC power and a current of 10 ampere is flowing through that secondary coil. (B) 10 volt AC power and a current of 10 amperes is flowing through that secondary coil. (C) 10 volt AC power and a current of 12 amperes is flowing through that secondary coil. (D) 12 volt AC power and a current of 12 amperes is flowing through that secondary coil.
C
Which of the following has/have a magnetic field? (A) An electrically polarized ball. (B) An electric charge and an electric current. (C) An electron and an electric current. (D) An electron and an electric charge.
C
You get on your bicycle and begin pedaling. You travel forward faster and faster and soon reach full speed. As you are picking up speed, friction between the ground and the bicycle wheels is exerting (A) zero force on the bicycle. (B) a backward force on the bicycle. (C) a forward force on the bicycle. (D) an upward force on the bicycle.
C
You have two identical electric space heaters, both of which are plugged into the same electrical outlet of your home. It's a cold winter day and you turn on one of the heaters. A current of 10 amperes flows through the wires of your home (to provide power to the heater) and wastes 1 watt in those wires. When you turn on the second heater, a current of (A) 40 amperes flows through the wires of your home and wastes 2 watts in those wires. (B) 10 amperes flows through the wires of your home and wastes 2 watts in those wires. (C) 20 amperes flows through the wires of your home and wastes 4 watts in those wires. (D) 20 amperes flows through the wires of your home and wastes 2 watts in those wires.
C
Your camera can't focus properly on a flower that is too close to it. When a flower is just a little too close for your camera to focus on it, (A) a virtual image of that flower forms behind the flower (farther from the lens than the flower is from the lens). (B) a real image of that flower forms in front of the image sensor (too close to the lens). (C) a real image of that flower forms behind the image sensor (too far from the lens). (D) a virtual image of that flower forms in front of the flower (between the flower and the lens)
C
A Blu-ray player uses a blue laser to read a Blu-ray disc, while a DVD player uses a red laser to read a DVD. A Blu-ray disc can store far more information than a DVD, even though they are the same size, because the blue laser beam (A) has a longer wavelength than the red laser beam, so the blue beam can detect smaller symbols recorded on the disc's surface. (B) has higher energy photons than the red laser beam, so the blue beam can detect the symbols recorded on the disc's surface more quickly. (C) has lower energy photons than the red laser beam, so the blue beam can detect the symbols recorded on the disc's surface more quickly. (D) has a shorter wavelength than the red laser beam, so the blue beam can detect smaller symbols recorded on the disc's surface.
D
A flashlight is powered by two 1.5 volt batteries that are connected in a chain to produces 3.0 volts. You turn the flashlight on to make sure that it works and then switch it off. While the flashlight remains off, the voltage difference between the two wires in the switch is (A) 1.5 volts. (B) 0.0 volts. (C) 0.75 volts. (D) 3.0 volts.
D
A nuclear fission chain reaction is sustained by neutrons: neutrons from one shattered nucleus induce fissions in other fissionable nuclei. Those fissions also release protons, but protons don't induce fissions because (A) protons do not have enough mass to cause fissions. (B) protons do not have enough momentum to cause fissions. (C) protons do not have enough energy to cause fissions. (D) protons are repelled by nuclei.
D
A person who is "nearsighted" sees nearby objects clearly but can't focus on a distant landscape. That landscape appears blurry because each eye forms its real image in front of the retina. To move the real image of the landscape away from the lens so that its image forms on the retina, the person should wear glasses that contain (A) short-focal length converging lenses. (B) low f-number converging lenses. (C) long-focal length converging lenses. (D) diverging lenses.
D
A simple electric generator consists only of a permanent magnet rotor that spins near a coil of wire. This generator produces (A) direct current electric power that increases in voltage as the angular speed of the rotor increases. (B) direct current electric power. The voltage of that power does not depend on the rotor's angular speed. (C) alternating current electric power that increases in frequency as the angular speed of the rotor increases. The voltage of that power does not depend on the rotor's angular speed. (D) alternating current electric power that increases in both frequency and voltage as the angular speed of the rotor increases.
D
An acorn falls 20 meters from the high branch of an oak tree to the ground. This fall takes about 2 seconds [assume the acceleration due to gravity is 10 m/s2]. After it has fallen for only 1 second, the acorn is still falling and is located (A) 10 meters above the ground. (B) considerably less than 10 meters above the ground. (C) a little less than 10 meters above the ground. (D) considerably more than 10 meters above the ground.
D
Around high tension power lines there are (A) magnetic fields, but no electric fields. (B) neither electric nor magnetic fields. (C) electric fields, but no magnetic fields. (D) both electric and magnetic fields.
D
If the speed of light in water did not depend on the wavelength of that light, a rainbow would (A) still appear red on the outside and violet on the inside. (B) appear reversed in color, with red on the inside and violet on the outside. (C) not appear at all. (D) appear white.
D
If you put a magnetic compass in a uniform magnetic field, the compass needle will experience a (A) force in the direction of the magnetic field. (B) torque no matter which way the needle is pointing. (C) force in the direction opposite the magnetic field. (D) torque unless the needle is aligned with the magnetic field or aligned opposite the magnetic field.
D
Separating uranium-235 from uranium-238 is extremely difficult because (A) uranium-235 is extremely radioactive. (B) uranium-235 and uranium-238 both have the same number of neutrons. (C) uranium-235 is unstable and falls apart during the separation process. (D) uranium-235 and uranium-238 are chemically indistinguishable.
D
Soon after the water in a fountain leaves the nozzle and begins its flight up into the air, it breaks up into round balls of water. As one of these water balls travels upward it experiences (A) an upward force that decreases gradually and reaches zero at the moment the ball reaches its peak height. (B) an upward force that diminishes gradually and reaches zero at the moment the ball returns to the height at which it left the nozzle. (C) an upward force that remains constant until the ball reaches its peak height and then becomes a downward force. (D) no upward force.
D
Suppose that you have purchased a fluorescent lamp that was accidentally manufactured without the white coating on the inside of its glass tube. You can see right through the glass tube, which appears empty. When you turn that lamp on, it will emit (A) brilliant white light from a thin line down the center of the glass tube. (B) the same diffuse white light that it would emit if it had the white coating. (C) no light at all. (D) a dim bluish glow.
D
Suppose you suspend a copper wire above the north pole of a strong permanent magnet. You connect the two ends of that wire to a headphone plug and insert that plug in your iPod. When you press "play", the iPod sends an alternating current representing sound through the wire. The wire (A) accelerates along its length because of energy from the magnetic pole. (B) accelerates alternately toward and away from the magnet's north pole because of electromagnetic attraction and repulsion. (C) does not accelerate because electric charges are neither attracted nor repelled by magnetic poles. (D) accelerates back and forth perpendicular to both the magnetic field and the current it is carrying because of the Lorentz force.
D
The electric motor in a toy car has a permanent magnet rotor and stationary electromagnets. When the motor is propelling the car, the poles of its electromagnets (A) repel the rotor's poles as they approach and repel the rotor's poles as they separate. (B) attract the rotor's poles as they approach and attract the rotor's poles as they separate. (C) repel the rotor's poles as they approach and attract the rotor's poles as they separate. (D) attract the rotor's poles as they approach and repel the rotor's poles as they separate.
D
To an astronaut on the space station, stars appear as steady points of light. On earth, those same stars appear to twinkle because their light is being bent very slightly in directions that change with time. What is bending the starlight in a time-dependent manner? (A) The earth's rotation but not its orbit around the sun. (B) Both the earth's rotation and its orbit around the sun. (C) The earth's orbit around the sun but not its rotation. (D) The earth's windy and turbulent atmosphere.
D
Two of your friends are pulling on opposite ends of a rope in the game of "tug of war". At this moment, your friend on the left is winning: both of them are moving to the left at constant velocity. The net force on the rope (A) points toward the right. (B) points toward the left. (C) points straight down. (D) is zero.
D
When a light wave consisting of one photon of red light passes through an appropriate laser medium, it will stimulate the emission of light. The light that emerges from the laser medium is (A) a collection of independent light waves that have exactly the same wavelength as the original light wave. (B) a collection of independent light waves that are traveling in exactly the same direction as the original light wave. (C) a collection of independent light waves that have exactly the same frequency as the original light wave. (D) a single light wave that is exactly like the original light wave, except that it consists of many photons.
D
When a long piece of wire is carrying a 1-ampere current, the wire exhibits a voltage drop of 1 volt. When that wire is carrying a 2-ampere current, the wire's voltage drop is (A) 4 volts. (B) 1 volt. (C) 0.5 volts. (D) 2 volts.
D
You are at the county fair and are throwing objects at a stack of heavy milk bottles. If you can push the bottles off the far end of the table, you'll win a giant stuffed animal. The objects you can throw are (1) a beanbag that doesn't bounce or stick, (2) a blob of putty that doesn't bounce but sticks to anything it hits, and (3) a rubber ball that bounces well and doesn't stick. Assuming that you give each of these three objects the same momentum when you throw them, which object is most likely to push the bottles off the table? (A) Since you throw them with equal momenta, they are equally good at pushing the bottles off the table. (B) The blob of putty (item 2). (C) The beanbag (item 1). (D) The rubber ball (item 3).
D
You are standing on the shore of a small lake and you see the opposite shore reflected in the lake's calm surface. You are trying to photograph the fish swimming in the lake, but the reflection of the shore makes it hard to see the fish. To eliminate most of that reflection, you should put a filter in front of the camera's lens that blocks (A) long wavelength light. (B) short wavelength light. (C) vertically polarized light. (D) horizontally polarized light.
D
You have three batteries: a 9.0-volt battery and two 1.5-volt batteries. Using clips and wires, you can link these batteries together in various chains. The possible voltage rises that you can obtain with these batteries are (A) 1.5 volts, 3.0 volts, 9.0 volts, 10.5 volts, and 12.0 volts. (B) 1.5 volts, 3.0 volts, and 9.0 volts. (C) 1.5 volts, 3.0 volts, 9.0 volts, and 10.5 volts. (D) 1.5 volts, 3.0 volts, 6.0 volts, 7.5 volts, 9.0 volts, 10.5 volts, and 12.0 volts.
D
You have two simple camera lenses, both 1 inch in diameter, but one has a much longer focal length than the other. Compared to the short focal length lens, the long focal length lens forms real images that are (A) smaller and brighter. (B) larger and brighter. (C) smaller and dimmer. (D) larger and dimmer.
D