Download Chapter 20 (Electricity) Practice Test

Name: ________________________ Class: ___________________ Date: __________
ID: A
Chapter 20 (Electricity) Practice Test
Modified True/False
Indicate whether the sentence or statement is true or false. If false, change the identified word or phrase to make the
sentence or statement true.
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1. Electric charges that are different attract each other. _________________________
____
2. Conduction is the transfer of electrons from a charged object to another object by rubbing.
_________________________
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3. The unit of measure of voltage is the ohm. _________________________
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4. As the temperature of most conductors increases, the resistance decreases. _________________________
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5. For a constant voltage, increasing the resistance will cause the current to decrease.
_________________________
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6. In a parallel circuit, there is only one path for current to take. _________________________
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7. If one light bulb is removed from a parallel circuit with three bulbs, the brightness of the other bulbs will
decrease. _________________________
8. Like charges ____________________ and opposite charges ____________________.
9. When a pathway through which charges can move forms suddenly, _________________________ occurs.
10. The SI unit of electric current is the ____________________.
11. Scientists usually define the direction of current as the direction in which ____________________ charges
would flow.
12. Wood, plastic, and rubber are good electrical ____________________, and copper is a good electrical
____________________.
13. The SI unit of resistance is the ____________________.
14. Potential difference is measured in _________________________.
15. A complete path through which charge can flow is an electric ____________________.
16. To calculate power, multiply voltage measured in ____________________ by ____________________
measured in amps.
17. The transfer of excess charge through a conductor to Earth is called ____________________.
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18. Electric force is ____________________ proportional to the amount of charge and
____________________ proportional to the square of the distance between the charges.
19. A material that has almost zero resistance when it is cooled to low temperatures is a(an)
_________________________.
Figure 20-1
20. In Figure 20-1, where is the field of each charge the strongest?
21. What is a charge’s electric field?
22. What are three ways that a charge can be transferred?
23. What is the law of conservation of charge?
24. What is the difference between direct current and alternating current?
25. Explain why metal wire coated with plastic or rubber is used in electric circuits.
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26. What is the voltage in a circuit if the current is 3 amps and the resistance is 3 ohms? Explain your answer.
27. If the voltage is 90 volts and the resistance is 30 ohms, what is the current? Explain your answer.
28. How much energy does a 50-watt light bulb use compared to a 100-watt light bulb if both are shining for
the same length of time? Explain your answer.
29. What is a circuit breaker?
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Use the diagram to answer each question.
30. Which circuit—A or B—represents a series circuit? Explain your answer.
31. Which circuit—A or B—is a parallel circuit? Explain your answer.
32. Which circuit diagram represents circuit B?
33. What will happen to bulb 1 in circuit A if the switch is opened?
34. Will removing bulb 1 in circuit B cause bulb 3 to go out? Explain.
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35. What will happen to bulb 2 in circuit diagram D if bulb 1 burns out?
36. Suppose you have one light bulb in a simple circuit. If you add a second identical light bulb in series, what
would happen to the brightness of the first bulb? If instead you add the second bulb in parallel, what would
happen to the brightness of the first bulb? Explain your answers.
37. Why does plugging too many appliances into the same circuit cause too much current to flow through the
circuit? What can happen as a result?
38. How are friction, induction, and static discharge involved in lightning?
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39. How are conduction and induction alike and how are they different?
40. Explain why you may produce a static discharge if you touch a metal doorknob after walking on a wool
carpet.
41. How is current related to resistance?
42. What is the resistance of a lamp operating at 115 volts and using 0.25 amp of current? What relationship
did you use to find the answer?
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Figure 20-2
43. Are both circuits in Figure 20-2 series circuits? Explain your answer.
44. In which direction do the electrons move in Figure 20-2? How does this compare to the direction of the
current?
45. Based on the circuit diagrams in Figure 20-2, what would happen if one of the bulbs in Circuit A burned
out? What would happen if one of the bulbs in Circuit B burned out? Explain your answers.
46. In Figure 20-2, what device could be added to the circuits to open the circuits? Explain how this device
works. Compare this device to safety devices that stop the current in a home.
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Figure 20-3
47. Compare the resistance in the three circuits shown in Figure 20-3 when the switches are closed. Explain the
cause of any differences.
48. In Figure 20-3, how will the current compare in Circuits A, B, and C when the switches are closed? Explain
your answer.
49. When the switches are closed in Figure 20-3, which bulbs will be the brightest and which will be the
dimmest? Assume that all of the light bulbs and batteries are identical. Explain your answer.
50. Using the same materials, how could you change the circuits in Figure 20-3 so that all the bulbs would have
the same brightness? Explain your answer.
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