µ GCSE | Induction

10 quick questions - for GCSE or iGCSE

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10 minutes maximum!

(can you do it in 5?)

Induction and transformers

Physics only! - Not Double Science.

1. What does 'induction' mean?

  • A. The production of a force on a conductor due to a magnetic field.
  • B. The production of a force on a conductor due to friction.
  • C. The production of a voltage in a conductor due to a magnetic field.
  • D. The production of a voltage in a conductor due to friction.

 

2. The image shows an aluminium rod placed between 2 magnets.

How can a voltage be induced in this rod between the ends labelled A and B?

  • A. Replace the north pole with another south pole.
  • B. Change the aluminium rod for a copper rod.
  • C. Move the rod upwards or downwards.
  • D. Heat the rod.

 

3&4. A magnet is dropped through a coil connected to a millivoltmeter as shown. The voltmeter needle moves to the right showing a positve reading.

magnet dropped through coil

 

3. Which of these will make the voltmeter reading smaller but still positive?

  • A). Drop the south pole through first.
  • B). Add more turns to the coil.
  • C). Move the magnet slowly through the coil.
  • D). Use a stronger magnet.

4. Which of these will make the voltmeter move to the left?

  • A). Drop the south pole through first.
  • B). Add more turns to the coil.
  • C). Move the magnet slowly through the coil.
  • D). Use a stronger magnet.

 

5. The diagram shows an a.c. generator - a coil is rotated between two magnets to produce a voltage to heat a resistor.

from www.ncert.nic.in

Which of these sentences here best describes the changes that take place if the coil is rotated faster?

  • A. The alternating voltage across the resistor and the frequency both remain constant.
  • B. The alternating voltage across the resistor remains constant, but the frequency of the a.c. increases.
  • C. The alternating voltage across the resistor increases and the frequency also increases.
  • D. The alternating voltage across the resistor increases but the frequency stays the same.
6. A device that uses sound waves to move a coil can induce a small voltage signal in an external circuit that represents the sound. It is converting the energy in sound waves into electrcial energy.  

What is the name given to this device?

  • A. A loudspeaker.
  • B. A dynamo.
  • C. A generator.
  • D. A microphone.

7-9. A transformer is used to increase or decrease the voltage for an appliance.

What are the missing values in the table below?

Transformer formula:

(diagram www.coolschool.ca)
  Input Voltage (V)
Number of turns on primary
number of turns on secondary
output voltage (V)
7.
20
100
500
8.
12
1600
240
9.
12
400
60

10. The national grid uses step up transformers to produce very high voltages in long cables that link towns and cities. Why is this?

  • A. People are less likely to steal the electrcial energy because it is dangerously high voltage.
  • B. The transformers step up the power delivered by the same ratio as the step up in voltage.
  • C. Houses and offices need this very high voltage to operate.
  • D. Less current is needed, and therefore there is less power loss in the cables.