Name: ________________________ Class: ___________________ Date: __________
ID: A
Exam 2
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____
____
1. For this circuit, which of these equations is correct?
a. 80-1I2-20I2-30I1=0
c. 45-1I2-40I3-30I1=0
d. -30I1+20I2+1I2-80=0
b. I1+I3=I2
2. A current of 20 A flows through a wire of length 1 m and diameter 1 mm. The potential across the wire is
0.32 V. From this table of resistivities, select the material of the wire:
Material
Copper
Silver
Gold
Tungsten
Iron
a.
b.
c.
Copper
Silver
Gold
Resistivity(Ohm-m)
1.7x10-8
1.26x10-8
2.44x10-8
5.5x10-8
10.0x10-8
d.
e.
1
Tungsten
Iron
Name: ________________________
ID: A
____
3. What is the potential across the 8 Ω resistor?
____
a. 2 V
c. 4 V
b. 6 V
d. 16 V
4. In a single circuit within your house, what happens to the total current as you add electrical appliances?
____
____
____
a. the current stays the same
c. the current decreases
b. the current increases
d. none of these
5. You wish to measure a voltage across a resistor. You should connect the measuring device in what way?
a. in parallel with the resistor
c. in series with the resistor
b. replace the resistor with the measuring
d. it depends on the circuit
device
6. The GFCI measures which of these?
a. Voltage
c. Current
b. Potential
d. Power
7. A 2.0 V potential difference is maintained across a 10. Ω resistor for a period of 2.0 minutes. What total
charge passes through the resistor in this time?
a.
b.
40 C
24 C
c.
d.
2
0.40 C
10. C
Name: ________________________
____
____
ID: A
8. What is the required resistance of your hot water heater element if you are to heat 25 kg of water from 0 °C to
20°C in 30 minutes. Assume the heater operates at 220 V. (The specific heat of water is 4186 J/kg °C)
c. 420 Ω
a. 40 Ω
b. 3 Ω
d. 10,000 Ω
9. If the ammeter in this circuit reads a current of I 3=2 A. What is the current I 1?
a.
b.
1.4 A
0.7 A
c.
d.
3
0.4 A
1.25 A
Name: ________________________
ID: A
____ 10. An RC circuit has a resistance of 3 MΩ in series with a capacitor of 2 µF. After 25 seconds, has the
capacitor fully charged?
a. No
c. Not enough information
b. Yes
____ 11. When you rotate the knob of a light dimmer, what is being changed:
I. Resistance
II. Potential
III. Current
IV. Power
a.
b.
III and IV
II only
c.
d.
I, III, and IV
II and III
____ 12. When 2 or more resistors are connected in parallel to a battery,
the total current flowing from the
battery equals the sum of the currents
flowing through each resistor
a.
all of the above
c.
b.
the equivalent resistance of the
combination is less than or equal to
the resistance of any one of the
resistors
d. the voltage across each resistor is the
same
____ 13. A heater with a resistance of 5 Ω is connected to a potential of 100V. How much energy is output in 20
seconds?
a.
b.
10,000 J
40,000 J
c.
d.
4
20,000 J
25 J
Name: ________________________
ID: A
____ 14. In this circuit, how much brighter or dimmer is bulb A compared with bulb C? Assume the bulbs have the
same resistance.
A
C
B
10 V
a.
b.
c.
A is 4 times as bright as C
A is 1/4 as bright as C
A is 1/2 as bright as C
d.
e.
A is twice as bright as C
A has the same brightness as C
____ 15. In this RC circuit, the time constant is 1 s and the resistance is 10 MΩ. What is the capacitance, C?
a.
b.
c.
1 µF
10 µF
0.1 µC
d.
e.
5
0.1 µF
2 µF
Name: ________________________
ID: A
____ 16. Two identical light bulbs are connected either in series or parallel to identical batteries. Which circuit gives
the most light?
a.
b.
the parallel circtuit
they are both the same
c.
d.
the series circuit
not enough information
c.
d.
8A
none of these
____ 17.
In this circuit, if I 1=2 A and I3=4 A, what is I2?
a.
b.
2A
6A
6
Name: ________________________
ID: A
____ 18. What is the current in this circuit?
a. 3.1 A
c. 0.63 A
b. 2.0 A
d. 0.32 A
____ 19. When you apply a potential of 3 V to a particular electrical device, the current in 1 A. When you apply 6V,
the current is 2 A. Is this device Ohmic or Non-Ohmic?
a. Ohmic
c. Neither
b. Non-Ohmic
d. Not enough information
____ 20. Two lightbulbs operate at 120 volts. One is brighter than the other. Which has the higher resistance?
a. they have the same resistance
c.
b. the brighter one
d.
____ 21. The third prong on electrical outlets provides what:
a. an emergency switch
c.
b. more stability for the electrical plug
d.
7
the dimmer one
not enough information
a current measuring device
an alternate ground
Name: ________________________
ID: A
____ 22. If the switch S is closed, what happens to the potential across R 2?
a. decreases
c. stays the same
b. increases
d. not enough information
____ 23. Two wires, A and B, have the same physical dimensions. The resistance of wire A is 1/2 that of wire B.
How do their resistivities compare?
c. ρA= ρB
a. ρA=2 ρB
b. ρA=4 ρB
d. ρA= ρB
____ 24. What does GFCI an abbreviation for?
a. Great Food Comes Interspersed
c. Ground Fault Current Instrument
b. Ground Fault Circuit Interrupt
d. Ground saFety Circuit Instrument
____ 25. On a circuit breaker, you have a 1200 W heater and a 720 W fan. When you add a 240 W blender, the circuit
breaker turns off. Assume all the devices operate at 120 V. Which of these is the maximum allowed current
for the breaker?
a. 17 A
c. 13 A
b. 19 A
d. 8 A
____ 26. The electric company charges a rate of $0.10 per kilowatt-hour. How much does it cost to run a 100 W bulb
for 10 hours?
a.
b.
$0.36
$0.10
c.
d.
8
$1
$10
Name: ________________________
ID: A
____ 27. What is the equivalent resistance of this circuit?
a. 0.8 Ω
b. 5 Ω
____ 28. The answer to this question is “B”
a. A
b. B
c.
d.
8Ω
4Ω
c.
d.
C
D
9
ID: A
Exam 2
Answer Section
MULTIPLE CHOICE
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