Chapter 7: Magnetism and Its Uses
Name______________
Block_______
1. If a generator coil makes 6000 revolutions in 2 minutes, how many revolutions does it make each second?
a. 50 revolutions/s
c. 0.05 revolutions/s
b. 12,000 revolutions/s
d. 3000 revolutions/s
2. How many turns are in the secondary coil of a step-down transformer that reduces a voltage from 900 V to 300 V and has 15
turns in the primary coil?
a. 30 turns
c. 60 turns
b. 3 turns
d. 5 turns
3. How many turns are in the secondary coil of a step-down transformer that increases voltage from 30 V to 150 V and has 7 turns
in the primary coil?
a. 30 turns
c. 35 turns
b. 150 turns
d. 1 turn
4. The current produced by an AC generator switches direction twice for each revolution of the coil. How many times does a 110
Hz alternating current switch direction each second?
a. 880 times/s
c. 220 times/s
b. 55 times/s
d. 440 times/s
5. The coil of a 60 Hz generator makes 60 revolutions each second. How many revolutions does the coil make in 5 minutes?
a. 12 revolutions
c. 720 revolutions
b. 18,000 revolutions
d. 300 revolutions
6. A step-down transformer reduces voltage from 2400 V to 120 V. What is the ratio of the number of turns in the primary coil to
the number of turns in the secondary coil of the transformer?
a. 2280 / 1
c. 20 / 1
b. 1 / 20
d. 288,000 / 1
7. What is the output voltage from a step-down transformer with 200 turns in the primary coil and 100 turns in the secondary coil
if the input voltage was 750 V?
a. 375 V
c. 75 V
b. 750 V
d. 1,500 V
8. How many turns are in the primary coil of a step-down transformer that reduces a voltage from 400 V to 100 V and has 80 turns
in the secondary coil?
a. 160 turns
c. 40 turns
b. 20 turns
d. 320 turns
9. What is the output voltage from a step-up transformer with 25 turns in the primary coil and 75 turns in the secondary coil if the
input voltage was 120 V?
a. 60 V
c. 240 V
b. 360 V
d. 40 V
10. What effect does increasing the current flowing in the wire have on an electromagnet?
a. it has no effect on the electromagnet.
b. it decreases the strength of the magnetic field.
c. it causes it to become a permanent magnet.
d. It increases the strength of the magnetic field.
11. Which of the following changes electrical energy into mechanical energy?
a. electric motor
c. generator
b. superconductor
d. transformer
12. Why does the north pole of a compass point toward Earth’s geographic north pole?
a. Earth’s geographic north pole is a south magnetic pole.
b. Opposite poles repel.
c. Like poles attract.
d. A compass does not rely on Earth’s magnetic field to function.
13. Which of the following is a form of electromagnetic induction?
a. using an electromagnet to measure electric current
b. changing electrical energy to mechanical energy that produces sound
c. producing electric current by moving a magnet through a wire loop
d. producing mechanical energy by sending electric current through an electromagnet
14. The __________ are regions where the magnetic force exerted by a magnet is strongest.
a. anodes
b. magnetic poles
c. cathodes
d. magnetic field lines
Chapter 7: Magnetism and Its Uses
15. The primary coil of a step-up transformer has ten turns and its secondary coil has 100 turns. What is the voltage in the
secondary coil if the input voltage in the primary coil is 50 V?
a. 5,500 V
c. 160 V
b. 4,500 V
d. 500 V
16. Iron is a magnetic material, but an iron nail does not behave like a magnet because __________.
a. its magnetic domains are arranged randomly
b. it contains too few magnetic domains
c. its magnetic domains are aligned
d. the atoms in the iron exert a force on all the other atoms
17. Which of the following best describes how electricity is generated for homes?
a. Nuclear reactions cause electric current to flow around the reaction chamber.
b. Water released from a dam generates electric current, which is transformed into mechanical energy.
c. Steam pushes turbine blades in a generator, which changes the mechanical energy into an electric current.
d. The spinning of a windmill’s blades creates electric current without a generator.
18. Which of the following is found in all magnets?
a. a transformer
c. a north pole and a south pole
b. an electrical field
d. a geographic pole
19. When a bar magnet is broken into two pieces, each piece has a north and south pole because __________.
a. the magnetic poles have been isolated
b. the magnetic fields reversed
c. every magnet is made of many aligned smaller magnets
d. bar magnets are permanent magnets
20. Which of the following devices produces electric current?
a. generator
c. galvanometer
b. stereo speaker
d. electric motor
21. Which of the following elements is magnetic/
a. lead
c. iron
b. aluminum
d. tin
22. Electric current should pass through a __________ after being transmitted by a power plant and before it enters your home.
a. step-up transformer
c. turbine
b. step-down transformer
d. generator
23. North poles of magnetic always attract __________.
a. positive charges
c. other north poles
b. south poles
d. negative charges
24. __________ flows in only one direction through a wire.
a. Alternating current
c. Voltage
b. Electric current
d. Direct current
25. Which of the following devices can increase or decrease the voltage of an alternating current?
a. battery
c. generator
b. galvanometer
d. transformer
26. Why doe power plants commonly produce alternating current?
a. Less resistance is created in the wire.
b. Voltage of alternating current can be increased or decreased with transformers.
c. It does not lose energy as heat when transmitted over long distances.
d. It is more economical to produce.
27. the interaction between two magnets is called __________.
a. magnetic force
c. current
b. a magnetic field
d. polarity
28. The magnetic field that surrounds a magnet exerts __________.
a. resistance
c. electrical current
b. air pressure
d. the magnetic force
29. Electric current passing through a wire produces __________.
a. a magnetic field around the wire
c. a permanent magnet
b. a compass
d. geographic poles