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# Several problems regarding basic electrical quantities

1. In alternating current, the motion of the charges
a. continuously changes in the forward and reverse directions.
b. is equal to the speed of light.
c. is greater than the speed of light.
d. in the direction of the electric field.

2. A flashlight bulb with a potential difference of 4.5 V across it has a resistance of 8.0 ohm. How much current is in the bulb filament?
a. 3.7 A
b. 1.8 A
c. 9.4 A
d. 0.56 A

3. Which of the following wires would have the LEAST resistance? (Assume that the wires have the same cross-sectional area.)
a. an aluminum wire 10 cm in length
b. an aluminum wire 5 cm in length
c. a copper wire 10 cm in length
d. a copper wire 5 cm in length

4. When compared in a given time interval with other light bulbs in a 120 V outlet, a 60 W light bulb
a. converts the same electrical energy to heat and light than a 40 W light bulb.
b. converts more electrical energy to heat and light than a 100 W light bulb.
c. converts less electrical energy to heat and light than a 40 W light bulb.
d. converts less electrical energy to heat and light than a 100 W light bulb.

#### Solution Preview

<br>1. In alternating current, the motion of the charges
<br>a. continuously changes in the forward and reverse directions.
<br>b. is equal to the speed of light.
<br>c. is greater than the speed of light.
<br>d. in the direction of the electric field.
<br>
<br>
<br>The definition for an alternating current taken from
<br>http://encyclopedia.thefreedictionary.com/Alternate%20current:
<br>
<br>"An alternating current (AC) is an electrical current , where electrical charge oscillates rather than flowing continuously in one direction as is ...

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