# Unit 9 Review

1. A charge of 0.30 Coulombs has a potential energy of 400 Joules has an electric potential (i.e., voltage) of ___ Volts.

1. 1300
2. 400
3. 120
4. 0.0075

2. If a Van de Graff Generator has an electric potential (i.e., a voltage) of 600 Volts and a charge of 0.000001 Coulombs. What is the PE of the charge?

1. 6.0 X 108 J
2. 600 J
3. 6 X 10-4 J

3. If you were to grab onto a single wire (suspended above the ground by the wire only) that was at a potential of 1000 Volts,

1. You should make sure that you are insured.
2. You would not have any current flow since there is no electric potential difference.
3. There will be a current, but your resistance is so large that you will not be electrocuted.

4. In the water analogy, current is like

1. water flow.
2. water pressure.

5. In an electrical circuit, electrons come from _____________.

1. a dry cell, wet cell or battery
2. the back emf of motors
3. the power station generator
4. the electrical conductor itself
5. none of these

6. The source of electrons lighting an incandescent light bulb is ________.

1. the power company
2. electrical outlet
3. atoms in the light bulb filament
4. the wire leading to the lamp
5. the source voltage

7. In a common circuit, electrons move at speeds of ____________.

1. a fraction of a centimeter per second
2. many centimeters per second
3. the speed of a sound wave
4. the speed of light
5. none of these

8. The number of electrons delivered to an average American home by an average power utility in 1984 was ______________

1. zero
2. 110
3. 220
4. billions of billions
5. none of these

9. Two lamps, one with a thick filament and one with a thin filament, are connected in series. The current is greater in the lamp with the ____________.

1. thick filament
2. thin filament
3. the same in each lamp

10. Two lamps, one with a thick filament and one with a thin filament, are connected in parallel to a battery. The voltage in greatest across the lamp with the _____________.

1. thick filament
2. thin filament
3. both voltages are the same

11. Two lamps, one with a thick filament and one with a thin filament, are connected in parallel to a battery. The current is largest in the lamp with the _____________.

1. thick filament
2. thin filament
3. current is the same in both

12. Two lamps, one with a thick filament and one with a thin filament are connected in series to a battery. The voltage is greater across the lamp with the ____________.

1. thick filament
2. thin filament
3. voltage is the same for both

13. As more lamps are put into a series circuit, the overall current in the circuit _____________.

1. increases
2. decreases
3. stays the same

14. As more lamps are put into a parallel circuit, the overall current in the circuit ____________.

1. increases
2. decreases
3. stays the same

15. A 60 W light bulb and a 100 W light bulb are each rated at 120 V. Which light bulb has a larger resistance?

1. the 60 W bulb
2. the 100 W bulb
3. both have the same resistance

16. 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 ___________.

1. \$0.22
2. \$0.55
3. \$2.20
4. \$5.50
5. none of these

Consider the following light bulb for questions #38 and #39. A light bulb has 144-ohm when it is placed across a 120 V potential difference.

17. The current going through the light bulb is ___ Amps.

1. 1.0
2. 0.83
3. 1.2
4. 4.0

18. The power rating of the bulb is ___ Watts.

1. 40
2. 60
3. 80
4. 100

19. A circuit has a current of 2.0 Amps. How many Coulombs of charge pass through the circuit in 3.0 seconds?

1. 2.0 C
2. 3.0 C
3. 4.0 C
4. 6.0 C

20. Find the voltage, current, and resistance where it is needed below.