Multiple Choice
Identify the
letter of the choice that best completes the statement or answers the question.
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| 1. | When
we say an appliance uses up electricity, we really are saying that a. | electrons are
taken out of the circuit and put somewhere else. | b. | electron kinetic
energy is changed into heat and other forms of energy. | c. | the main power
supply voltage is lowered. | d. | current disappears. | e. | electric charges
are dissipated. | | |
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| 2. | As
more lamps are put into a series circuit, the overall current in the circuit a. | stays the
same. | b. | increases. | c. | decreases. | | |
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| 3. | A
short circuit occurs when a. | the positive wire is connected directly to the negative
wire. | b. | very short wires are used in the
circuit. | c. | current lasts in the circuit for only a short
time. | d. | all of the above | e. | none of the
above | | |
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| 4. | Compared to thin wires, electrical resistance in thick wires is a. | less. | b. | the same. | c. | greater. | | |
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| 5. | A
15-ohm resistor has a 5-A current in it. What is the voltage across the resistor? a. | 5
V | b. | 15
V | c. | 20
V | d. | 25
V | e. | more than 25
V | | |
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| 6. | A
heater uses 21 A when connected to a 110-V line. If electric power costs 10 cents per kilowatt-hour
in this location, the cost of running the heater for 13 hours is _____. a. | $0.30 | b. | $0.75 | c. | $3.00 | d. | $7.51 | e. | none of the
above | | |
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| 7. | When
resistors are put in parallel with each other their overall resistance is a. | smaller than the
resistance of any of the resistors. | b. | larger than the resistance of any other
resistor. | c. | the same as the resistance of one of the
resistors. | | |
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Problem
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| | 8. | A
30-V potential difference is applied across a parallel combination of an 8.0-ohm resistor and a
3.0-ohm resistor. A) Sketch the circuit. B) Find the equivalent resistance C) find the total
Current, D) What is the current in the 8.0-ohm resistor? E) Support your answer in terms of physics
concepts.
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