Unit 7 Electricity and Magnetism Review with answer key

Name:____________________________________________________Date:__________Block:__________
Unit 7: Electricity and Magnetism Review
Multiple Choice. Circle the letter of the correct answer(s).
1. If two charges attract each other, the two charges must be
A. Positive and negative
B. Positive and positive
C. Negative and negative
D. Both B and C
2. If two charges repel each other, the two charges must be
A. Positive and negative
B. Positive and positive
C. Negative and negative
D. Both B and C
3. An atomic particle that carries a neutral charge is a(n)
A. Proton
B. Electron
C. Neutron
D. Quark
4. An atomic particle that carries a positive charge is a(n)
A. Proton
B. Electron
C. Neutron
D. Quark
5. An atomic particle that carries a negative charge is a(n)
A. Proton
B. Electron
C. Neutron
D. Quark
6. Three ways of giving an object a charge are conduction, induction, and
A. Friction
B. Convection
C. Direct current
D. Alternating current
7. The law of electric charges states that
A. mass = force x acceleration
B. the mass and energy of charges are the same
C. objects must move to produce electric current
D. opposite charges attract and like charges repel
8. An object that loses or gains electrons becomes
A. discharged
B. charged
C. generated
D. conducted
9. Conductors are materials through which charges move
A. easily
B. slowly or are stopped
C. both A and B
D. neither A nor B
10. Insulators are materials through which charges moves
A. easily
B. slowly or are stopped
C. both A and B
D. neither A nor B
11. Resistance is
A. the flow of electric charges along a conductor
B. opposition to the flow of electricity
C. the loss of static electricity as charges move off an object
D. the buildup of charges on an object
12. Electric current is
A. the flow of electric charges along a conductor
B. opposition to the flow of electricity
C. the loss of static electricity as charges move off an object
D. the buildup of electric charges on an object
13. Charges that constantly switch flowing from one direction to flowing in the reverse direction are
A. Multiple current
B. Direct current
C. Alternating current
D. Static electricity
14. What do we call a device that can convert chemical energy to electric energy?
A. A plant
B. A generator
C. A battery or dry cell
D. A transformer
15. Buildings use this device to protect against electrical fires.
A. A generator
B. A fuse
C. A circuit breaker
D. Both B and C
16. The type of current that is used in the outlets of your house and in this school is
A. Alternating current
B. Direct current
C. Static electricity
D. Amperes
17. Static electricity is
A. the flow of electric charges along a conductor
B. opposition to the flow of electricity
C. a nuclear reaction
D. the buildup of charges on an object
18. Lightning is an
A. Electric discharge
B. Electric charge
C. Electrical conduction
D. Electrical induction
19. Electric discharge is
A. When static electricity moves off an object
B. When static electricity builds up on an object
C. Opposition to the flow of electricity
D. A nuclear reaction
20. Charges flowing in the same direction are called
A. Multiple current
B. Static electricity
C. Alternating current
D. Direct current
21. All circuits must include these three things: an energy source, a load, and
A. wires
B. a battery
C. a light bulb
D. a switch
22. Length, temperature, and thickness all affect
A. convection
B. radiation
C. transformation
D. resistance
23. What do we call a device that increases the voltage of an alternating current?
A. Galvanometer
B. Electric motor
C. Step up transformer
D. Step down transformer
24. What unit do we use to measure the number of electrons that move past a point in a circuit in one
second?
A. Watt
B. Volt
C. Ohm
D. Ampere
25. What unit do we use to measure electrical resistance?
A. Watt
B. Volt
C. Ohm
D. Ampere
26. What unit do we use to measure the force or pressure (potential difference) in a circuit?
A. Watt
B. Volt
C. Ohm
D. Ampere
27. What do we call a device that uses electromagnetic induction to increase or decrease the voltage of
an alternating current?
A. Galvanometer
B. Radiometer
C. Transformer
D. Generator
28. What do we call a device that uses electromagnetic induction to convert kinetic energy into electrical
energy?
A. Galvanometer
B. Radiometer
C. Transformer
D. Generator
29. An electric hair dryer has an electric motor that changes
A. Thermal energy into electrical energy and potential energy
B. Kinetic energy into electrical energy and kinetic energy
C. Electrical energy into potential energy and thermal energy
D. Electrical energy into kinetic energy and thermal energy
30. A good insulator would be made of (choose all correct answers)
A. Plastic
B. Gold
C. Iron
D. Rubber
31. A good conductor would be made of
A. Cotton
B. Rubber
C. Wood
D. Lead
32. If you have a series circuit with two light bulbs and you add six more bulbs (in a series) to the same
circuit, what would happen to the brightness of the light bulbs?
A. no change
B. bulbs wouldn’t light up at all
C. bulbs would grow dimmer
D. bulbs would grow brighter
33. Which item labeled in this diagram is used to open and close a circuit?
A.
B.
C.
D.
1
2
3
4
34. Which item labeled in this diagram is a load or resistor?
(Choose all that are correct)
A. 1
B. 2
C. 3
D. 4
35. Which item in the circuit above is indicated by the symbol
A. Light bulb
B. Resistor
C. Switch
D. Battery
?
36. Which item in this diagram is the source of the electrons?
A. 1
B. 2
C. 3
D. 4
37. All magnets
A. are surrounded by a magnetic field
B. exert forces
C. have two poles
D. all of the above
38. If you cut a magnet in 2 pieces, you get
A. two pieces that are each a magnet
B. two pieces that are not magnetized
C. two pieces that are each north poles
D. two pieces that are each south poles
39. A compass needle is a
A. magnet that is free to rotate.
B. nonmagnetic piece of metal that is free to rotate.
C. fixed magnet.
D. fixed nonmagnetic piece of metal.
40. You can demagnetize a magnet if you
A. strike it very hard, drop it, heat it
B. cut it, drop it, heat it
C. strike it very hard, drop it, break it
D. all of the above
41. Magnetic force will push magnets apart if you hold
A. the north pole of one magnet near the south pole of another
B. the north pole of one magnet near the north pole of another
C. the south pole of one magnet near the south pole of another
D. both B) and C)
42. The magnetic field of a bar magnet is strongest near the
A. sides
B. ends
C. center
D. both B) and C)
43. You can increase the magnetic field of a solenoid by
A. Increasing the current
B. Putting iron inside the looped coils
C. Adding more loops to the coils
D. All of the above
44. Which diagram below illustrates a magnetized substance?
1
A.
B.
C.
D.
2
Diagram 1
Diagram 2
Diagram 1 and 2
Neither Diagram 1 or 2
Using the magnetic fields around the magnets A, B, and C shown above, answer questions #45-#47.
45. Which magnet is the strongest?
A. Magnet A
B. Magnet B
C. Magnet C
D. All of the magnets have the same strength
46. Which magnet is the weakest?
A. Magnet A
B. Magnet B
C. Magnet C
D. All of the magnets have the same strength
47. What is being illustrated in the diagram?
A. The make-up of magnets
B. The energy levels around magnets
C. That magnets have different strengths
D. That magnets all have the same strength
48. What is shown is this picture/diagram?
A. closed series circuit
B. open series circuit
C. closed parallel circuit
D. open parallel circuit
49. The diagram above shows a circuit that creates
A. static electricity and an insulated screw
B. resistance and a generator
C. a conductor and a motor
D. current electricity and a magnetic screw
50. A light emitting diode (LED) is considered to be a (an)
A. conductor
B. insulator
C. semiconductor
D. transistor
51. In the picture/diagram above, what is shown?
A. a parallel circuit
B. a series circuit
C. an In-line circuit
D. a static circuit
52. In the picture/diagram above, if one bulb goes out, what will the other bulb do?
A. remain lit
B. go out also
C. change color
D. get dimmer
Ohm’s Law states that the current is equal to the potential difference divided by the resistance. Use the
formulas given here to solve questions #53 and #54. Write in the number answer, using a period for a decimal
if needed.
53. How much current is needed to light a lamp that runs on 110 volts with a resistance of 40 ohms? _______
54. What would be the resistance of an electric fan that runs on 110 volts and draws 55 amperes of current?
___________
55. A transistor is used to amplify the electrical signal in which of the following?
A. TV remote
B. Radio
C. Generator
D. Motor
56. The diagrams below represent the magnetic domains within 2 different substances. Which is magnetized?
Diagram _________ (write the answer as a number).
Diagram 1
Diagram 2
57. In the diagram below, what numbers indicate the poles?
A. 1 and 1
B. 2 and 2
C. 3 and 3
D. None of the above
1. A
2. D
3. C
4. A
5. B
6. A
7. D
8. B
9. A
10. B
11. B
12. A
13. C
14. C
15. D
16. A
17. D
18. A
19. A
20. D
21. A
22. D
23. C
24. D
25. C
26. B
27. C
28. D
29. D
30. A and D
31. D
32. C
33. A
34. B and D
35. A
36. C
37. D
38. A
39. A
Answer Key for Unit 7 (Electricity and Magnetism) Review
40. A
41. D
42. B
43. D
44. B
45. C
46. A
47. C
48. B
49. D
50. C
51. B
52. A
53. 2.75
54. 2
55. B
56. 2
57. B