Download Chapter 16 Test A

Name: ________________________ Class: ___________________ Date: __________
ID: A
Chapter 16 Test A
Multiple Choice
Identify the choice that best completes the statement or answers the question.
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1. When current flows through a coil of wire, you have a(n):
a. superconductor.
b. electromagnet.
c. ceramic magnet.
d. semiconductor.
2. Hans Christian Oersted discovered that magnetism was related to electricity when he placed a compass needle
in the presence of a current carrying wire and the:
a. current immediately turned off.
b. current reversed direction.
c. compass needle moved as if the wire were a magnet.
d. compass needle always pointed north.
3. The magnetic field is strongest for a straight wire carrying electric current:
a. far from the wire.
b. close to the wire.
c. at one end of the wire.
d. There is no magnetic field around the wire.
4. The magnetic field is strongest for a wire carrying electric current that has been looped into a coil:
a. inside the coil.
b. outside the coil.
c. far away from the coil.
d. There is no magnetic field around the wire.
5. A simple electromagnetic device consisting of a coil with many turns is known as a:
a. solenoid.
b. electric motor.
c. semiconductor.
d. commutator.
6. An electric charge creates magnetism by:
a. static.
b. isolation.
c. moving.
d. domain.
7. If you increase the current in an electromagnet:
a. the north and south poles will be switched.
b. the magnetic field will be stronger.
c. the magnetic field will disappear.
d. a short circuit will be created.
8. Solenoids and other coil electromagnets are used in all the following devices EXCEPT:
a. speakers.
b. electric motors.
c. doorbells.
d. batteries.
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Name: ________________________
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ID: A
9. Two parallel current-carrying wires next to each other on a table are shown in the diagram:
If their currents are in opposite direction:
a. the wires will lift off the table.
b. the wires will move away from each other.
c. the wires will move toward each other.
d. nothing will happen.
____ 10. An electric current moving upward through a straight wire creates a magnetic field. The diagram that
correctly represents this magnetic field is:
a. A.
b. B.
c. C.
d. D.
____ 11. The purpose of a commutator in an electric motor is to:
a. spin around so the motor can do useful work.
b. create a voltage drop so that current flows.
c. switch the electromagnets from north to south and back again.
d. attract and repel the magnets in the rotor.
____ 12. The device that switches the polarity of the electromagnets giving motion to the rotor in an electric motor is
the:
a. armature.
b. commutator.
c. brush.
d. knife switch.
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Name: ________________________
ID: A
____ 13. The rotating element of a motor is referred to as the:
a. field coil.
b. brush.
c. commutator.
d. armature.
____ 14. The main parts of a motor include all of the following EXCEPT a :
a. rotating element with magnets.
b. double-throw knife switch.
c. stationary magnet surrounding the rotor.
d. commutator.
____ 15. An electric motor spins because:
a. the voltage pushes the motor around.
b. an electromagnet attracts and then repels magnets in the rotor.
c. it is converting mechanical energy to electrical energy.
d. the electric current is always flowing in the same direction.
____ 16. A motor’s basic function is to convert ____ to ____.
a. electrical energy, mechanical energy.
b. alternating current, direct current.
c. mechanical energy, electrical energy.
d. high voltage, low voltage.
____ 17. The diagram below represents the rotor of an electric motor:
To cause the rotor to turn in a counter-clockwise direction, the north pole of a magnet should be placed at
position:
a. A.
b. B.
c. C.
d. D.
____ 18. The device that uses electromagnetic induction to produce electricity is called a:
a. motor.
b. rotor.
c. turbine.
d. generator.
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Name: ________________________
ID: A
____ 19. When a magnet moves into a coil of wire, electric current is caused to flow by:
a. conduction.
b. reduction.
c. induction.
d. deduction.
____ 20. An electric generator produces:
a. electrical energy.
b. chemical energy.
c. mechanical force.
d. variable force.
____ 21. According to Faraday’s law of induction, the faster a magnet is moved in and out of a coil:
a. the greater the current produced.
b. the less current produced.
c. the greater the capacitance produced.
d. the less capacitance is produced.
____ 22. A transformer efficiently changes current and voltage:
a. using electromagnetic induction.
b. using alternating current.
c. without changing power.
d. All of the above
____ 23. Electromagnetic induction occurs when:
a. electromagnets are induced in a wire.
b. electrons are induced in a magnet by a moving wire.
c. current is induced in a wire by an moving magnet.
d. a magnetic field is induced into a coil of wire by a current.
____ 24. A current can be induced to flow in a coil in all of the following situations EXCEPT:
a. holding a powerful magnet in the middle of a coil of wire.
b. sliding a bar magnet into a coil of wire.
c. moving a coil of wire toward an electromagnet.
d. dropping a coil of wire over a bar magnet.
____ 25. A generator’s basic function is to convert ____ to ____.
a. electrical energy, mechanical energy.
b. alternating current, direct current.
c. mechanical energy, electrical energy.
d. high voltage, low voltage.
____ 26. The motion of a magnet that induces the greatest alternating current to flow in a coil is:
a. rapid movement in one direction through the coil.
b. rapid back and forth movement of the magnet in the coil.
c. slow movement in one direction through the coil.
d. no motion of the magnet.
____ 27. The battery charger for a rechargeable drill contains a transformer that converts 120 volt household voltage to
the 6-volts required by the drill battery. If the primary coil of the transformer has 200 turns, how many turns
are on the secondary coil?
a. 200
b. 60
c. 20
d. 10
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Name: ________________________
ID: A
____ 28. A step down transformer has a primary voltage of 120 volts. The primary coil has 30 turns, and the secondary
coil has 3 turns. The secondary voltage is ____ volts.
a. 360
b. 30
c. 12
d. 9
____ 29. An alternating current is produced by an electric generator because the:
a. chemical energy increases and decreases each turn.
b. nuclear energy increases and decreases each turn.
c. magnetic field increases and decreases each turn.
d. magnetic field remains the same each turn.
____ 30. You want to build a transformer that steps up voltage. You will need:
a. more turns in the primary coil than the secondary coil.
b. more turns in the secondary coil than the primary coil.
c. the same number of turns in the primary and secondary coils.
d. Not enough information given.
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