Conceptual physics oct 24- Nov 9 Exam
9. why are red, green and blue called the additive primary colors?
Adding appropriate amounts of red plus green plus blue lights can produce almost any color of the spectrum.
54. your friend says that microwaves and ultraviolet light have different wavelengths but travel through space at the same speed. Do you agree or disagree.
Agree. In vacuum, all electromagnetic waves travel at c, the speed of light.
55. The circuit within an incandescent lamp is shown. Which of the battery arrangements will light the lamp?
The circuit in the center is a complete circuit and will light the lamp.
25. Distinguish between an umbra and a penumbra.
The umbra is the central, darker part of a shadow where light is totally blocked. The penumbra is the lighter part of a shadow where light is partially blocked.
30. what is the function of fuses or circuit breakers in a circuit?
When the circuit is overloaded, the fuse blows and breaks the circuit. Thus, fuse or circuit breakers are used to protect lines.
9. When is the angle at which a ray of light strikes glass not the same as the angle it exits?
When the light strikes the glass in one medium (such as air) and exits the glass in another medium (such as water)
7. Will water flow more easily through a wide pipe or a narrow pipe? will current flow more easily through a thick wire or a thin wire?
Wide pipe and thick wire
48. The bulbs shown are identical. An ammeter is placed in different locations, as shown. Rank the current readings in the ammeter from greatest to least.
-A=B=C
49. All bulbs are identical in the circuits shown. An ammeter is connected next to the battery, as shown. Rank the current readings in the ammeter, from greatest to least.
-C, B, A
5. which warms more quickly in sunlight: a colorless or a colored piece of glass?
A colored piece of glass warms quickest because it absorbs more frequencies of light, thus converting the energy to temperature.
2. What condition is necessary for the sustained flow of water in a pipe? What analogous condition is necessary for the sustained flow of charge in a wire?
A continuous pressure difference, often provided by a pump, is needed for water to flow. A continuous potential difference, often provided by a battery, is needed for charge to flow.
25. Distinguish between a converging lens and a diverging lens.
A converging lens is thicker in the middle and rays of light that are initially parallel are made to converge. A diverging lens is thinner in the middle and the rays of light are made to diverge.
78. if a large enough electric field is applied, even an insulator will conduct as electric current, as is evident in lighting discharges through the air. explain how this happens, taking into account the opposite charges in an atom and how ionization occurs.
A neutral atom in an electric field is electrically distorted (see Figure 21.11 on page 381). If the field is strong enough, the distortion results in ionization, where the charges are torn from each other. The ions then provide a conducting path for an electric current.
16. What is a photon?
A particle of light. It has not mass, no charge, and possesses energy, frequency and wavelength. Wave-Particle Duality.
6. What is a positive ion? a negative ion?
A positive ion is a neutral atom that has lost one or more electrons. A negative ion is a neutral atom that has gained one or more electrons.
18. Why does a transformer require ac?
A voltage is induced only when the magnetic field is changing.
82. how does an incident radio wave affect the electrons in a receiving antenna?
A wave and hit piece of metal electron. Wave mixture electro field and electron applies an force to an electron charge. Oscillate.
18. Why does the sky normally appears blue?
Air molecules have resonances in the ultraviolet, so they scatter blue light more than red light. These particles emit light most strongly in the UV region, so they have natural frequencies higher than that of visible light. This means that blue light will be closer in frequency that red light, scattered more strongly.
8. What is meant by saying charge is quantized?
All charged objects have a charge that is an integer multiple of the charge of an electron.
6. What is the principal difference between a radio wave and visible light? between visible light and an x-ray
All electromagnetic waves travel at the same speed in air (or a vacuum), 3.00 X 108 m/s. What makes the waves different is the fact that they have different frequencies and wavelengths. Radio waves have long wavelengths and low frequencies compared to visible light while X-rays have short wavelengths and high frequencies compared to visible light.
4. How does the charge of one electron compare to that of another electron? How does it compare with the charge of a proton?
All electrons have the same charge. Electron charge is equal and opposite to the proton charge. A proton has 1800 times the mass of an electron.
21. In terms of net charge, how does an electrically polarized object differ from an electrically charged object?
An electrically polarized object can have zero net charge, while a charged object cannot have zero net charge. Polarized: one side of atom is more +, other side is more -. Charged: entire atom is either + or - charged.
69. why does a high flying airplane cast little or no shadow on the ground below while a low flying airplane casts a sharp shadow?
Any shadow cast by a faraway object such as a high-flying plane is filled in mainly by light tapering in from the Sun, which is not a point source. This tapering is responsible for the umbra and penumbra of solar eclipses. If the plane is low to the ground, however, the tapering of light around the airplane may be insufficient to fill in the shadow, part of which can be seen.
39. If you place a chunk of iron near the north pole of a magnet, attraction will occur. Why will attraction also occur if you place the same iron near the south pole of the magnet.
Attraction will occur because the magnet induces opposite polarity in a nearby piece of iron. North will induce south, and south will induce north.
45. Bar magnets are moved into the wire coils in identical quick fashion. Voltage inducted in each coil causes a current, as indicated on the galvanometer.
B, C, A
46. The transformers are each powered with 100 W, and all have 100 turns on the primary. The umber of turns on each secondary varies as indicated. a) 240V- 50 turnsb) 240V - 200 turnsc) 240V - 100 turns
B, C, A Vb, Vc, Va
48. Shown are three separate pairs of point charges. Assume the pairs interact only with each other. rank the magnitudes of the force between the pairs from largest to smallest. A) -4q<---------x--------->+2q B) +3q<--------x--------->+3q C) +2q----------x/2---------->-2q
BAC
48. In which of these cases will a ripe banana appear black- when illuminated with red, yellow, green, or blue lights?
Blue light would make the banana black because blue is the direct opposite of yellow since green and red stimulate yellow.
1. which has the higher frequency, red light or blue light?
Blue. The lowest frequency light we can detect appears to most people as the color red, and the highest frequency as violet.
5. How do magnetic poles differ from electric charges?
Charges can be isolated and poles cannot
23. What are eddy currents?
Eddy currents are induced swirls of electrons in a conducting sheet, as opposed to a conducting wire.
1. Cite a major difference between electrical and gravitational forces?
Electrical forces can attract or repel, whereas gravitational forces only attract.
80. We know that the source of a sound wave is a vibrating object, a guitar string for example. What vibrating object produces an electromagnetic wave?
Electro magnetic, magnetic or electron
21. What is the error in saying the source of electrons in a circuit is the battery or generator?
Electrons are already in the wire. The battery and generators are the only sources of energy
3. Why are electrons, rather than protons, the principal charge carriers in metal wires?
Electrons are free to move through the metal, whereas protons are fixed in place.
50. Why is charge usually transferred by electrons rather than by protons?
Electrons are loosely bound on the outside of atoms, whereas protons are very tightly bound within the atomic nuclei.
23. Why are metals shiny?
Free electrons in metals vibrate when light strikes them, thereby reemitting the light as reflected light.
10. Is it correct to say that a generator produces energy? defend your answer.
Generators do not produce energy. Instead, they convert it from some other form to electrical energy
59. Two charged particles are projected into a magnetic field that is perpendicular to their velocities. If the particles are deflected in opposite directions, what does this tell you about them?
If both particles carry the same charge they were initially opposite directions. if they carry opposite charges they were traveling in the same direction
10. What is the difference between an unmagnetized iron nail and a magnetized iron nail at the micro level?
In an unmagnetized nail, the magnetic domains have a random orientation so that the net magnetism adds to zero. In a magnetized nail, many of the magnetic domains are aligned.
5. What are the basic differences and similarities between a generator and an electric motor?
In both, moving electrons experience a force. The motor transforms electrical energy to mechanical energy. The generator transforms mechanical energy to electrical energy
1. In what way does incident light that falls on an object affect the motion of electrons in the atoms of the object?
Incident light makes the electrons oscillate. The electrons then emit light or absorb the light and convert it to heat.
66. Two separate similar coils of wire are mounted close to each other, as shown. The first coil is connected to a battery and has a direct current flowing through it. The second coil is connected to a galvanometer.
Induction occurs only for a change in the intercepted magnetic field. The galvanometer will display a pulse when the switch in the first circuit is closed and current in the coil increases from zero. When the current in the first coil is steady, no current is induced in the secondary and the galvanometer reads zero. The galvanometer needle will swing in the opposite direction when the switch is opened and current falls to zero.
8. Does heating a metal wire increase or decrease its electrical resistance?
It increases resistance because atoms at higher temperatures jostle into the way of moving electrons.
20. What effect does earth's magnetic field have on the intensity of cosmic rays striking earth's surface?
It reduces the intensity. Still, "secondary" cosmic rays reach Earth's surface, greatest at magnetic poles, and decreases away from the poles; smallest at equatorial regions.*ex. aurora borealis and australis.
15. if you look with a magnifying glass at pictures printed in full color in books or magazines, you'll notice three colors of ink plus black. what are these colors?
Magenta, cyan, and yellow
3. What are the three ways in hich voltage can be induced in one or more loops of wire?
Move a magnet near the loop, move the loop near a magnet, change current in a nearby loop
7. What is meant by conservation of change?
Net charge cannot be created or destroyed.
83. If you fire a bullet through a board, it will slow down inside and emerge at a speed that is less than the speed at which it entered. does light, then, similarly slow down when it passes through a glass and also emerge at a lower speed? defend your answer.
No, there is a delay -> conservation of energy
59. is it necessary for a charged body actually to touch the ball of the electroscope for the leaves to diverge? defend your answer.
No. It is not necessary for the charged body to touch the ball of an electroscope. If a negative charge is simply brought near, some electrons in the ball are repelled and driven to the gold leaves, leaving the ball positively charged. Or if a positive charge is brought near the ball, some electrons will be attracted and move up to the ball to make it negative and leave the leaves positively charged. This is charge separation due to induction. (If by small chance you are attempting an answer to this question without having witnessed this, pity, pity, pity! Better that your time is spent studying the physics of familiar things.)
48. What is the fundamental source of electromagnetic radiation?
Oscillating electric charges
4. in what way does light interact with a pigment?
Pigment is a dye color. It reflect or absorb. It absorb red and it would be cyan. Cyan, magenta and yellow.
75. Measurements show that there is an electric field surrounding earth. Its magnitude is about 100 N/ C at earth's surface, and it points inward toward Earth's center. From this information, can you state whether earth is negatively or positively charged?
Planet Earth is negatively charged.
8. What is the color of the lowest frequency of visible light? of the highest frequency?
Red has lowest frequency and longest wavelength. Violet has highest frequency and shortest wavelength.
59. which requires a physical medium in which to travel: light, sound, or both? defend your answer?
Sound. Sound is a pressure wave that requires a medium to propagate. Light is an electromagnetic wave, and does not.
4. Cite the law of reflection
The angle of incidence equals the angle of reflection.
8. How does the angle at which a ray of light strikes a pane of window glass compare with the angle at which it passes out the other side?
The angles are the same.The emerging light is displaced but parallel to the incident light.
14. Does a battery produce dc or ac? does the generator at a power station produce dc or ac?
The battery is dc; the generator is ac.
27. When charges mutually repel an distribute themselves on the surface of conductors, what becomes of the electric field inside the conductor?
The charges arrange themselves to make the field inside the conductor zero. (ex: in sphere, in car)
26. Why are there probably no permanently aligned magnetic domains in earth's core?
The core is too hot to allow atoms to maintain a constant magnetic orientation.
58. A proton moves in a circular path perpendicular to a constant magnetic field. If the field strength of the magnet is increased, does the diameter of the circular path increase, decrease, or remain the same?
The diameter of the circular path decreases.
2. Why does gravitation between Earth and the moon predominate?
The electric force between Earth and Moon cancels out because they have an equal number of positive and negative charges.
16. What effect does a piece of iron in a current-carrying loop have on magnetic field strength?
The electromagnetic field of the current-carrying loop is amplified because it aligns the domains in the iron.
4. What exactly is an ampere?
The flow of one coulomb per second
19. In what direction relative to a magnetic field does a moving charged particle experience maximum deflecting force? Minimum deflecting force?
The force is greatest when the particle moves in a direction perpendicular to the magnetic field lines. At other angles, the force is less, and it becomes zero when the particle moves parallel to the field lines.
82. A free electron and a free proton are placed in the same electric field. (A) How will the forces acting on them compare? (B) How will their accelerations compare? (C) How will their directions of travel compare?
The forces are equal in magnitude, opposite in direction.Work Step by Step The electric force on a charge q in an electric field E is given by qE. The charges on a proton and electron are equal and opposite. The forces they experience in the same electric field are therefore also equal and opposite.
63. Something gets "Used up" in a battery that eventually dies and goes flat. One friend says that current is used up. Another friend says that energy is used up. Who, if either, do you agree with, and why?
The friend who says energy is used up is correct.
13. In chapter 22, we learned that the direction of the electric field about a point charge is radial to the charge. What is the direction of the magnetic field surrounding a current-carrying wire?
The magnetic field is directed along concentric circles surrounding the wire.
2. What must change in order for electromagnetic induction to occur in a wire coil?
The magnetic field through the coil must change.
12. why are metals good conductors both of heat and of electricity
The outer shell electrons in metals are free to move from atom to atom.
28. How do the rods in the eye differ from the cones?
The rods are rod-shaped and are more sensitive to dim light; cluster in periphery.
3. What is the source of an electromagnetic wave?
The source of an electromagnetic wave is vibrating electric and magnetic fields.
11. what is the speed of light after exiting a glass lens into air?
The speed is a c after exiting a glass lens into air.
5. Relative to the distance of an object in front of a plane mirror, how far behind the mirror is the image?
The virtual image is the same distance behind the plane mirror as the object is in front of it. The virtual image and object will have the same size.
25. Which of these is a unit of power and which is a unit of energy a wart, kilowatt or kilowatt hour?
The watt and kilowatt are units of energy, while a kilowatt-hour is a unit of power.
92. A car's headlights dissipate 40 W on low beam and 50 W on high beam. In which setting, high or low beam, is there less resistance in the lamp filament?
There is less resistance in the high beam. Fewer Ohms (resistance) allows more amps to flow to the bulb, therefore making the bulb brighter.
11. why are red and cyan called complementary colors?
They can be added together to make white light.
24. Light normally travels in a straight lines, but it "bends" in an optical fiber. Explain
Total internal reflection keeps the light trapped inside the optical fiber.
18. True or false: A charged particle must move in a stationary magnetic field in order to experience a force due to the field
True
14. What is the fate of the energy of ultraviolet light that is incident upon a glass?
Ultraviolet light will be absorbed by the resonant vibration of electrons and turned into internal energy and a temperature increase.
22. Why do opaque materials become warmer when light shines on them?
Vibrations given by the light to their electrons, atoms, and molecules that absorb the light become internal energy, thus leading to a temperature increase.
14. Which of these does a transformer change: voltage, current, energy, power?
Voltage and current
49. Why is a generator armature harder to rotate when it is connected to a circuit and supplying electric current?
Work must be done to move a current-carrying conductor in a magnetic field. It's also a matter of energy conservation. There has to be more energy input if there is more energy output.
51. A magnet exerts a force on a current- carrying wire in figure 24.15. Does a current carrying wire exert a force on a magnet? why or why not?
Yes, it does. Since the magnet exerts a force on the wire, the wire, according to Newton's third law, must exert a force on the magnet.
13. when something is painted red, what color is most absorbed?
cyan, the complementary (opposite) color
26. What is the focal length of a lens?
focal lens. It will refract and create a local focus. It will spread out again.
78. Which will do less damage: plugging a 110 v hairdryer into a 220 v circuit or a 220 v hairdryer into a 110 v circuit? Defend your answer.
less damage is done with a 220V Hairdryer and 110V circuit because if it was reverse it would over heat because of too much current.
10. The index of refraction of water is 1.33. what does this say about the relative speeds of light in water and in a vacuum?
lights slow down by 25 percent. bigger index, the slower of light
30. What affects the size of the pupil of the eye other than the amount of light incident upon in?
our emotions!
8. what is a radiation curve?
radiation curve happens by each wavelength.
36. why do color scientists not list black and white as colors of lights?
they do not have specific wavelengths
46. What colors of ink do laser printers use to produce a full range of colors? do the colors form by color addiction or by color subtraction?
three color of ink. Cyan, magenta and yellow.
78. How do the two photos of California poppies relate to each other?
you wouldn't and it a hideous sight. to see better. green are sensitive.
