Download PHY-1020 Exam 3 Spring/Summer 2006

PHY-1020
Exam 3
Spring/Summer 2006
Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
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1. Two charged objects separated by a distance d exert an electrical force on each other. The distance d is
tripled. The electrical force on each body now
a. decreases by a factor of 9.
b. decreases by a factor of 3.
c. stays the same, since it is independent of the distance.
d. increases by a factor of 3.
e. increases by a factor of 9.
2. An external force does positive work to separate charges. In this process the charges gain
a. voltage
b. potential difference
c. potential energy
d. kinetic energy
e. power
3. The process of rearranging charges in an electrically neutral object in the external electric field is called
a. charging.
b. polarization.
c. induction.
d. electrization.
e. self-charging.
4. Can a point charge act with an electric force on a neutral conducting object?
a. Yes, and the electric force is attractive.
b. Yes, and the electric force is repulsive.
c. Yes, and the direction of the force depends on the sign of the charge.
d. No, because the electric force acts only between charged objects.
5. The direction of overall motion of actual charge carriers
a. always coinsides with the conventional direction of the electric current - from the higher
potential to the lower potential.
b. depends on the signs of carriers.
6. If three identical bulbs are connected in parallel across a 3V battery, the voltage across each bulb will be
a. 1/3V.
b. 1V.
c. 3V.
d. 9V.
7. If three identical bulbs are connected in series across a 3V battery, the voltage across each bulb will be
a. 1/3V.
b. 1V.
c. 3V.
d. 9V..
8. A car headlight and an interior dome light use the same voltage, but the headlight consumes much more
power because
a. its resistance is lower.
b. the current in it is smaller.
c. of the way it is connected.
d. All of the above.
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9. Given two lengths of the same wire, the resistance of the longer wire
a. is larger than the shorter wire.
b. is smaller than the shorter wire.
c. is the same as the shorter wire.
d. could be more or less depending on the composition.
e. could be more or less depending on the temperature.
10. Electromagnetic waves are created by
a. electric charge at rest.
b. magnets.
c. accelerating electric charge.
d. magnetic monopoles.
e. none of the above.
11. A coil of wire is connected to a galvanometer. When a bar magnet is moved in and out of the coil, the
galvanometer records a current. The current results because
a. the coil acts like a transformer.
b. the changing magnetic field induces an electric field in the wire.
c. an electromagnetic wave is generated.
d. the wire is ferromagnetic.
e. none of the above.
12. You do not see your image when you look at a flat rough aluminum surface because of
a. interference.
b. diffraction.
c. specular reflection.
d. diffuse reflection.
e. polarization.
13. The colors of solid objects we see by reflected light are due to
a. interference.
b. selective absorption.
c. specular reflection.
d. polarization.
14. Light spreads out when it passes through a narrow slit because of
a. interference.
b. diffraction.
c. specular reflection.
d. diffuse reflection.
e. polarization.
15. If you are driving down a highway at 65 mph with your headlights on, what is the speed of the light emitted
from your headlights as seen by a person driving a car towards you at 70 mph?
a. c+135 mph.
b. c-5 mph .
c. c+5 mph.
d. c-135 mph.
e. c.
16. If an electron is bound to a nucleus, its _______ energy must be _________.
a. potential... positive
b. kinetic... negative
c. total... negative
d. total... positive
____ 17. As an electron is moving through a resistance in a circuit,
a. its potential energy increases.
b. the electric force does positive work.
c. the external force does positive work.
d. its voltage increases.
e. its voltage drops.
____ 18. A bulb with a resistance of 10 Ω (at room temperature) is connected to a 3V battery. As the temperature of the
bulb increases, the current through it
a. decreases.
b. remains the same.
c. increases.
d. The possible change cannot be predicted.
____ 19. A voltage in a power line is usually stepped up mainly to
a. increase the current for consumers.
b. reduce the current to reduce ohmic losses.
c. increase the power for consumers.
d. reduce the power to reduce ohmic losses.
e. keep the birds or animals away from damaging the lines.
____ 20. Magnetic force is caused by
a. magnetic charges
b. electric charges
c. moving magnetic charges
d. moving electric charges
e. there is no magnetic force
____ 21. An image formed in a conventional camera is always
a. virtual.
b. real.
c. neither of these.
____ 22. An image formed using a converging lens as a magnifying glass is
a. real.
b. virtual.
c. neither of these.
____ 23. The main reason for using AC power vs. DC power is
a. that all generators generate an alternating current.
b. that the AC is easy to step up or down.
c. that AC flows in both directions and devices work more effectively.
d. historical, we will use the DC power in the future.
e. We are actually using DC power.
____ 24. The image in a flat mirror is
a. virtual.
b. real.
c. neither of these.
____ 25. A rainbow is a result of
a. total internal reflection.
b. dispersion.
c. interference.
d. refraction.
e. all of the above.
26. Arrange the EM waves in the order from higher frequency to the lower: gamma rays, infrared, microwave,
radio, visible light, ultraviolet, x-rays
Gamma, x-rays, UV, visible, IR, microwave, radio
27. Arrange the visible light waves in the order from larger wavelength to the shorter: blue, green, orange, red,
violet, yellow.
red, orange, yellow, green, blue, violet
28. Point out the three similarities and two differences between the electric and gravitational force.
the electric force
the force of gravity
Similarities
Proportional to product of properties: charges, q1 × q 2 , and masses, m1 × m2 , respectively.
Inversely proportional to the square of distance between two point objects.
Both forces are central: the direction of the forces is along the line connecting two point
objects.
Differences
Can be both repulsive and attractive
Always attractive
Much stronger force
Much weaker force