Resistance and Ohm's Law
1. The ratio of the potential difference across a conductor to
the current in the conductor is called
(1) conductivity
(3) charge
(2) resistance
(4) power
2. A manufacturer recommends that the longer the extension
cord used with an electric drill, the thicker (heavier gauge)
the extension cord should be. This recommendation is made
because the resistance of a wire varies
(1) directly with length and inversely with cross-sectional
area
(2) inversely with length and directly with cross-sectional
area
(3) directly with both length and cross-sectional area
(4) inversely with both length and cross-sectional area
3. If the length of a copper wire is reduced by half, then the
resistance of the wire will be
(1) halved
(3) quartered
(2) doubled
(4) quadrupled
4. A piece of wire has a resistance of 8 ohms. A second piece
of wire of the same composition, diameter, and
temperature, but one-half as long as the first wire, has a
resistance of
(1) 8 Ω
(3) 16 Ω
(2) 2 Ω
(4) 4 Ω
9. The current through a 10.-ohm resistor is 1.2 amperes.
What is the potential difference
across the resistor?
(1) 8.3 V
(3) 14 V
(2) 12 V
(4) 120 V
10. A 330.-ohm resistor is connected to a 5.00-volt battery. The
current through the resistor is
(1) 0.152 mA
(3) 335 mA
(2) 15.2 mA
(4) 1650 mA
11. The graph at the right shows how
the voltage and current are related
in a simple electric circuit. For any
point on the line, what does the
ratio of V to I represent?
(1) work in joules
(2) power in watts
(3) resistance in ohms
(4) charge in coulombs
12. The graph below shows the relationship between current
and potential difference for four resistors A, B, C, and D.
5. A complete circuit is left on for several minutes, causing
the connecting copper wire to become hot. As the
temperature of the wire increases, the electrical resistance
of the wire
(1) decreases
(3) remains the same
(2) increases
6. An incandescent light bulb is supplied with a constant
potential difference of 120 volts. As the filament of the bulb
heats up, its resistance
(1) increases and the current through it decreases
(2) increases and the current through it increases
(3) decreases and the current through it decreases
(4) decreases and the current through it increases
7. The resistance of a copper wire is measured to be 4 ohms at
20ºC. If the wire is heated to 30ºC, the resistance of the
wire will be
(1) zero ohms
(3) more than 4 ohms
(2) less than 4 ohms
(4) 4 ohms
8. If the diameter of a wire were decreased, its electrical
resistance would
(1) decrease
(3) remain the same
(2) increase
Which resistor has the greatest resistance?
(1) A
(3) C
(2) B
(4) D
13. Which voltage would cause a current of 0.5 ampere in a
circuit that has a resistance of 24 ohms?
(1) 6.0 V
(3) 24 V
(2) 12 V
(4) 48 V
14. A 0.686-meter-long wire has a cross-sectional area of 8.23
×10–6 meter2 and a resistance of 0.125 ohm at 20° Celsius.
This wire could be made of
(1) aluminum
(3) nichrome
(2) copper
(4) tungsten
Resistance and Ohm's Law
Answer Key
[New Exam]
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