15732546
Descrição
Quiz por Jeffrey Piggott, atualizado more than 1 year ago
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Criado por Jeffrey Piggott
aproximadamente 6 anos atrás
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Questão 1
Questão
An e.m.f. is induced across a wire when it moves through the magnetic field between the poles of a magnet.
Which electrical device operates because of this effect?
Responda
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A a battery
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B a cathode-ray tube
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C a generator
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D a motor
Questão 2
Questão
The diagram shows a flat, rectangular coil placed between the poles of a magnet.
There is a current in the coil that makes it turn in the direction shown in the diagram.
Which change would make the coil turn in the opposite direction?
Image:
Q2 (binary/octet-stream)
Responda
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A decreasing the current in the coil
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B increasing the number of turns on the coil
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C reversing both the direction of the current in the coil and the poles of the magnet
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D reversing only the direction of the current in the coil
Questão 3
Questão
A transformer has 1000 turns on its primary coil. An input voltage of 12 V is applied to the primary coil, and an output voltage of 120 V is induced across the secondary coil.
How many turns are on the secondary coil of the transformer?
Image:
Q3 (binary/octet-stream)
Responda
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A 100
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B 120
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C 1000
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D 10 000
Questão 4
Questão
Which diagram represents the voltage output of a simple a.c. generator?
Responda
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Image:Q4a (binary/octet-stream)
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Image:Q4b (binary/octet-stream)
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Image:Q4c (binary/octet-stream)
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Image:Q4d (binary/octet-stream)
Questão 5
Questão
A transformer has 400 turns on its secondary coil. An input voltage of 12 V is applied to the primary coil, and an output voltage of 120 V is induced across the secondary coil.
How many turns are on the primary coil of the transformer?
Image:
Q5 (binary/octet-stream)
Responda
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A 12
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B 40
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C 400
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D 4000
Questão 6
Questão
A step-up transformer is used before electricity is transmitted by overhead cables.
Which statement explains why the step-up transformer is used?
Responda
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A It increases the current to increase the speed at which the electricity travels.
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B It increases the current to reduce energy loss in the cables.
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C It increases the voltage to increase the speed at which the electricity travels.
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D It increases the voltage to reduce energy loss in the cables.
Questão 7
Questão
A current-carrying wire XY lies in the magnetic field between the two poles of a U-shaped electromagnet. A force acts on the wire XY because of the magnetic field.
Each of the following actions is carried out separately.
● The current in the wire XY is reversed.
● The magnetic field is reversed.
● Both the current in the wire XY and the magnetic field are reversed at the same
time.
How many of these actions cause the direction of the force on the wire XY to be reversed?
Image:
Q7 (binary/octet-stream)
Responda
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A 0
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B 1
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C 2
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D 3
Questão 8
Questão
A current-carrying coil in a magnetic field experiences a turning effect.
How can the turning effect be increased?
Responda
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A Increase the number of turns on the coil.
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B Reduce the size of the current.
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C Reverse the direction of the magnetic field.
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D Use thinner wire for the coil.
Questão 9
Questão
A transformer has 2400 turns on its primary coil and 200 turns on its secondary coil.
What input voltage is needed to give an output voltage of 240 V?
Image:
Q9 (binary/octet-stream)
Responda
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A 12 V
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B 20 V
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C 240 V
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D 2880 V
Questão 10
Questão
A student investigates electromagnetic induction. She has a bar magnet and a coil of wire that is connected to a sensitive ammeter.
Which movement does not cause a reading on the ammeter?
Image:
Q10 (binary/octet-stream)
Responda
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A moving the coil to the right
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B moving both the magnet and the coil to the left at the same speed.
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C moving both the magnet and the coil towards each other at the same speed
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D moving the magnet to the left
Questão 11
Questão
The primary coil of a transformer has 200 turns. This primary coil is connected to an a.c. power supply of 25 V.
A voltmeter connected across the secondary coil reads 50 V.
How many turns are on the secondary coil?
Image:
Q11 (binary/octet-stream)
Responda
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A 25
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B 100
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C 200
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D 400
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