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Phy101
Test 3
1) When the distance between two charges is
halved, the electrical force between the charges
A) halves.
B) quadruples.
C) is reduced by 1/4.
D) doubles.
E) none of these.
C) decreases.
2) The primary purpose of a lightning rod is to
A) induce within the structure to which it is
attached a charge opposite to that of charged clouds
overhead.
B) attract lightning and guide it to the ground.
C) cancel the electric field within the structure to
which it is attached.
D) discharge the structure to which it is attached.
9) A capacitor is used to store
A) energy. B) charge. C) both. D) neither.
3) When a car is struck by lightning, the resulting
electric field inside the car is
A) small enough to be safe for an occupant inside.
B) normally huge for a time longer than the
lightning stroke itself.
C) zero.
D) normally huge, but for a brief time.
4) Electric potential, measured in volts, is the ratio
of electric energy to amount of electric
A) voltage.
B) charge.
C) resistance.
D) current.
E) none of these.
5) Electrons are made to flow in a wire when there
is
A) an imbalance of charges in the wire.
B) a potential difference across its ends.
C) more potential energy at one end of the wire
than the other.
6) An ampere is a unit of electrical
A) current.
B) resistance.
C) pressure.
D) charge
E) voltage
F) electrical energy
7) Heat a copper wire and its electric resistance
A) increases.
B) remains unchanged.
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8) Stretch a copper wire so that it is thinner and the
resistance between its ends
A) decreases.
B) increases.
C) remains unchanged.
10) Superconductors are noted for their
A) low electric resistance.
B) high electric resistance.
C) absence of electric resistance.
11) A wire carrying a current is normally charged
A) not at all. B) positively. C) negatively.
12) On some early automobiles both headlights
went out when one bulb burned out. The headlights
must have been connected in
A) parallel. B) series.
C) perpendicular. D) haste.
13) Which statement is correct?
A) Current causes voltage.
B) Resistance is established across a circuit.
C) Charge flows in a circuit.
D) Voltage flows through a circuit.
14) When two lamps are connected in series to a
battery, the electrical resistance that the battery
senses is
A) less than the resistance of either lamp.
B) more than the resistance of either lamp.
C) none of these.
15) The direction of an electric field is the direction
of the force that the field would exert on
A) a neutral test charge.
B) an electron.
C) an atom.
D) a proton.
E) a molecule.
16) As more lamps are put into a parallel circuit,
the overall current in the power source
A) increases.
B) decreases.
C) stays the same.
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Phy101
Test 3
17) Magnetic domains normally occur in
A) iron.
B) copper.
C) silver.
D) all of these
E) none of these
18) Outside a magnet, magnetic field lines are
conventionally drawn from
A) north to south.
B) south to north.
C) either way
19) The net charge on a charged capacitor
depends on
A) the area of the capacitor plates.
B) the distance between the capacitor plates.
C) the medium between the capacitor plates.
D) All of the above choices are correct.
E) None of the above choices are correct – the
net charge is zero.
20) A capacitor is useful in
A) boosting the energy output of a circuit.
B) increasing the current in a resistor.
C) smoothing pulsed current.
D) switching dc to ac in a circuit.
E) increasing or decreasing voltage.
21) An iron nail is more strongly attracted to
the
A) north pole of a magnet.
B) south pole of a magnet.
C) north or south pole – no difference really.
22) Magnetism is due to the motion of
electrons as they
A) move around the nucleus.
B) spin on their axes.
C) Choices A and B are both correct.
D) None of the above choices are correct.
23) (2 points) The electrical force on a 2-C charge
is 60 N. What is the value of the electric field at
the place where the charge is located?
A) 20 N/C
B) 30 N/C
C) 60 N/C
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D) 120 N/C
E) 240 N/C
24) (2 points) An electrical diode is useful for
A) storing electrical energy.
B) voltage modification.
C) boosting voltage.
D) limiting current.
E) changing ac to dc.
25) (2 points) Alternating current is normally
produced by a
A) generator. B) battery.
C) both of these. D) neither of these.
26) (2 points) The current through two identical
light bulbs connected in series is 0.25 A. The
voltage across both bulbs is 110 V. The resistance
of a single light bulb is
A) 22 ohms.
B) 44 ohms.
C) 220 ohms.
D) 440 ohms.
E) none of these.
27) (2 points) A heater uses 20 A when used in a
110-V line. If electric power costs 10 cents per
kilowatt hour, the cost of running the heater for 10
hours is
A) $0.22.
B) $0.55.
C) $2.20.
D) $5.50.
E) none of these.
28) (2 points) What is the resistance of a 120-W
incandescent lamp connected to a 120-V power
supply?
A) 1 ohm
B) 60 ohms
C) 100 ohms
D) 144 ohms
E) none of these
29) (2 points) A 100-Watt lamp glows brighter than
a 25-Watt lamp. The electrical resistance of the
100-Watt lamp must be
A) the same. B) greater. C) less.
30) (2 points) A 10-ohm resistor has a 5-A current
in it. What is the voltage across the resistor?
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Phy101
Test 3
A) 5 V
B) 10 V
C) 15 V
D) 20 V
E) more than 20 V
31) (2 points) Two lamps, one with a thick filament
and one with a thin filament, are connected in
series. The current is
A) greater in the lamp with the thick filament.
B) greater in the lamp with the thin filament.
C) the same in each lamp.
32) (2 points) The source of all magnetism is
A) tiny pieces of iron.
B) tiny domains of aligned atoms.
C) ferromagnetic materials.
D) moving electric charge.
E) none of these
33) (2 points) If a steady magnetic field exerts a
force on a moving charge, that force is directed
A) opposite the motion.
B) in the direction of the motion.
C) at right angles to the direction of the motion.
34) (2 points) The field surrounding every moving
electron is
A) always magnetic but never electric.
B) always electric but never magnetic.
C) sometimes magnetic and sometimes electric.
D) always both electric and magnetic.
E) none of the above
35) (2 points) Magnetic field lines about a currentcarrying wire
A) extend radially from the wire.
B) circle the wire in closed loops.
C) Choices A and B are both correct.
D) None of the above choices are correct.
36) (2 points) Moving electric charges will
interact with
A) an electric field or a magnetic field.
B) only a magnetic field.
C) only an electric field.
D) none of these
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