Download 45 Questions in Exam 3 - How Things Work | PHYS 140 and more Exams Classical Physics in PDF only on Docsity!
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Page 1 of 12 pages
- An electron is a fermion and a photon is a boson. The spin values of the electron and photon are ___ and ___, respectively.
a. 0 ½ b. 1 0 c. 0 1 d. ½ 0
- A television set uses a magnetic field to deflect its electron beam horizontally. This magnetic field is able to steer the electron beam because
a. a moving charged particle can experience a force when it passes through a magnetic field. b. an electron always travels in the direction of the magnetic field. c. an electron always travels in the opposite direction of the magnetic field. d. a stationary charged particle can experience a force in a magnetic field.
- When you move a strong permanent magnet, whose North Pole is pointing downward, rapidly toward the right, just above a stationary, horizontal aluminum surface, that magnet will experience
a. a downward force attracting it to the aluminum and a rightward force trying to speed it up. b. an upward force repelling it from the aluminum and a leftward force trying to slow it down. c. an upward force repelling it from the aluminum and a rightward force trying to speed it up. d. a downward force attracting it to the aluminum and a leftward force trying to slow it down.
- Which of the following creates a magnetic field?
a. Both a moving electric charge and an electric field that changes with time. b. Only a moving electric charge. c. Only an electric field that changes with time. d. Only a constant electric field.
Page 2 of 12 pages
- You are playing a recorder. Initially you have all the holes covered, and then change notes such that only the first four holes closest to the mouthpiece are covered. The second note will be
a. higher than the first note. b. lower than the first note. c. the same as the first note.
- If you blow across the top of a half full bottle of soda you can produce a clear tone. If you take a drink of soda to reduce the amount of liquid in the bottle and try this again, the pitch (frequency) of the sound produced will
a. increase. b. stay the same. c. exactly double. d. decrease.
- The second harmonic vibration of a violin string, in which the string vibrates as two half-strings, has
a. the same frequency or pitch of the string's fundamental vibration, but twice the amplitude of vibration. b. a frequency or pitch half that of the string's fundamental vibration. c. the same frequency or pitch of the string's fundamental vibration, but half the amplitude of vibration. d. a frequency or pitch twice that of the string's fundamental vibration.
- Tightening the strings of a guitar
a. raises their frequency or pitch because it softens the restoring force. b. lowers their frequency or pitch because it stiffens the restoring force. c. lowers their frequency or pitch because it softens the restoring force. d. raises their frequency or pitch because it stiffens the restoring force.
Page 4 of 12 pages
- A guitar string vibrating in its fundamental mode (as a single arc) behaves as a harmonic oscillator, which means that the restoring force acting on the string is
a. proportional to how far it is from equilibrium and that its pitch (frequency) can vary but its volume (amplitude) cannot. b. proportional to how far it is from equilibrium and that its volume (amplitude) can vary but its pitch (frequency) cannot. c. independent of how far it is from equilibrium and that its volume (amplitude) can vary but its pitch (frequency) cannot. d. independent of how far it is from equilibrium and that its pitch (frequency) can vary but its volume (amplitude) cannot.
- When you blow gently across the top of a soda bottle, the air inside it vibrates as a harmonic oscillator and it emits a clear tone. If you replace the air in the bottle with helium, the bottle’s new tone will definitely occur at a
a. lower pitch (a lower frequency). b. lower volume (a smaller amplitude). c. higher pitch (a higher frequency). d. higher volume (a larger amplitude).
- Two speakers are producing sound at the same time producing beats. Speaker A produces sound at a frequency of 202 Hz. Speaker B produces sound at a frequency of 200 Hz. What will be the beat frequency?
a. 2 Hz b. 202 Hz c. 2 seconds d. 202 seconds
- To make a large surface wave on the ocean travel faster, you could
a. increase its amplitude. b. decrease its amplitude. c. decrease its wavelength. d. increase its wavelength.
Page 5 of 12 pages
- Why does a wave break?
a. Because the water is too shallow to form a complete crest. b. Because the water is too deep to form a complete crest. c. Because the wavelength of the water wave becomes too large. d. Because the wavelength of the water wave becomes too small.
- If you walk on a carpet and become negatively charged, you can avoid the shocks of static electricity by carrying a very sharp needle in your hand and holding it out before touching a metal doorknob or wall. How does that needle protect you from static electricity?
a. the needle emits negative charge into the air via polarization. b. the needle emits negative charge into the air via a corona discharge. c. the needle collects positive charge from the air via a corona discharge. d. the needle collects positive charge from the air via polarization.
- What is the net charge of the following charges: + 10 C, - 1 C and + 2 C?
a. +11 C b. −11 C c. +13 C d. +9 C
- You have two positively charged balls, each of which is experiencing a force of 1 Newton away from the other. If you separate them by twice as much, what force will each one exert on the other?
a. ½ Newtons b. ¼ Newtons c. 2 Newtons d. 4 Newtons
Page 7 of 12 pages
- You have just pulled your clothes from the dryer and find that a sock is clinging to your jeans with static electricity. You hold the jeans in one hand and the sock in the other and pull the two apart. As the jeans and sock move apart, the forces between them become weaker because the
a. electric charge on each garment diminishes as they move apart. b. electric charge on each garment increases as they move apart. c. forces between electric charges become weaker with increasing distance. d. electric current passing through each garment diminishes as they move apart.
- Electrostatic air cleaners use very thin wires to transfer electric charge to dust particles primarily because very thin wires
a. heat up more quickly and easily than thick wires. b. break easily, require frequent repair, and are a benefit to the manufacturer's service department. c. can be spaced more closely together so that sparks can jump more easily from one wire to the other. d. cause the electrically charged particles to be close together, so that their repulsion pushes some of them onto the air and dust.
- You are standing on a plastic bench that insulates you from your surroundings. Both you and the helium balloon you are holding are electrically neutral. You now rub the balloon against your sweater, so that the balloon becomes negatively charged, and then let the balloon float away. You are left
a. with no negative electrically charged particles in your body. b. with a negative electric charge. c. electrically neutral. d. with a positive electric charge.
- After combing your hair on a hot dry day, you do the DR experiment and find your comb can attract a stream of water because
a. water is charged positively and your comb is charged negatively. b. water is charged negatively and your comb is charged positively. c. the comb is uncharged but the water molecules are attracted to it because the water becomes charged when passing through the faucet. d. the water molecules, although neutral, are electric dipoles and are attracted to the charge on the comb.
Page 8 of 12 pages
- The resistance of the power wires that lead from your toaster oven to the wall, in comparison to the resistance of the coils that get hot and glow inside the oven, is
a. The same b. Higher c. Lower d. Zero
- Which of the following is an example of spontaneous symmetry breaking?
a. fluid b. paramagnet c. ferromagnet d. normal metal
- Which of the following is not an application of superconductors?
a. research magnets b. MRI c. personal computers d. cell phones
- What is an intrinsic property of all superconductors?
a. They can exhibit zero resistance b. They can expel magnetic field c. The can act as a perfect diamagnet d. All of the above
- At what temperature do superconductors have zero resistance?
a. zero degrees Celsius b. below the critical temperature c. all temperatures
Page 10 of 12 pages
- Which of the following is not a characteristic of a superconductor?
a. zero resistance b. perfect diamagnetism c. perfect magnetism
- Where was the microscopic theory of superconductivity discovered?
a. Lyden b. UIUC c. UNC d. Prague
- A battery
a. creates positive charge. b. pumps positive charge from its positive terminal to its negative terminal. c. creates negative charge. d. pumps positive charge from its negative terminal to its positive terminal.
- Four 1.5-V batteries placed end-to-end power a flashlight. If the current in the circuit is 3 A, what is the resistance in the bulb?
a. 0.5 Ω b. 4.5 Ω c. 1.0 Ω d. 2.0 Ω
- A flashlight is a simple circuit with only two batteries, a bulb, and a switch. When the flashlight is on, current flows through these objects, one after the next, over and over again. When you turn the switch off, the current soon stops flowing because
a. the switch's magnetic field drops to zero and it stops inducing current in the circuit. b. the current becomes AC, which is incompatible with the DC batteries. c. charges accumulate on either side of the open switch and repel any additional like charges that approach them from the bulb or battery. d. the switch's magnetic field drops to zero and it can no longer attract positive and negative charges from the battery.
Page 11 of 12 pages
