GCSEPhysics: Combined ScienceEdexcelExam Questions11. Electromagnetic Induction11.1 Electromagnetic Induction

Electromagnetic Induction (Edexcel GCSE Physics: Combined Science)

Exam Questions

36 mins6 questions
Easy
Medium
1a
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Figure 1 shows a labelled transformer supplying homes in a village with electricity from a power cable.

7-3-e-1a-transformer-question

Figure 1

Complete the following sentences using words from the box. 

Each word can be used once, more than once or not at all.

cobalt direct input
secondary output primary
nickel iron alternating

 

     

Part W labels the input .............................. current.

Part X is the .............................. coil.

Part Y is the .............................. coil.

Part Z is made from .............................. .

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1b
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(i)
State the type of transformer shown in the diagram in part (a).
[1]
 
(ii)
Explain how the diagram shows this type of transformer.
[1]

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1c
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Compare the voltage in each coil of the transformer in the diagram in part (a).

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2a
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The national grid allows power to be efficiently delivered across the UK.
 


Describe where a step-up transformer is used as part of the National Grid.

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2b
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A teacher writes a note about a transformer but intentionally misses out some words.


Complete the following sentences using the correct words from the box.

  

coil core current
ends magnetic wire

 

     

A transformer works because an alternating .............................. in the primary .............................. produces a changing .............................. field in the ..............................  and then in the secondary coil.

This induces an alternating potential difference across the .............................. of the secondary coil.

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2c
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Explain why it is beneficial for the current in power cables to be small.

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3a
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Figure 1 shows a magnet passing through a coil of wire connected to an ammeter.

7-3-e-3a-generator-effect--

Figure 1

Explain why the ammeter shows a non-zero reading.

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3b
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A student moves the magnet towards the coil, from right to left. 



Describe the force they experience while moving the magnet.

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3c3 marks

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The student performs different actions and records the different ammeter readings they make for each action. 

Use statements from the box to describe the ammeter reading for each action. The first one has been completed for you. 

Needle doesn't move Needle moves to 0.8 A Needle moves to −0.4 A    

   

Action of student Reading on ammeter
Hold magnet still and move coil slowly towards magnet Needle moves to 0.8 A
Hold magnet still inside the coil
   		  
Move the magnet and coil together very quickly
   		  
Flip the magnet around and move slowly towards the coil  

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14 marks
A student uses a plotting compass to investigate the magnetic field around a wire.

Figure 10 shows the wire going straight through a card.

compasses

Figure 10 shows the compass needle when there is no current in the wire.

(i)
Which of these shows a possible direction of the compass needle when there is a current in the wire going from P to Q?
[1]
compasses-2
(ii)
Describe how the student could develop the investigation to find the shape of the magnetic field produced by the current.
[3]

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24 marks

Higher Only

There is an alternating current of 3 A in the primary coil of a transformer.

There is an alternating current of 6 A in the secondary coil of the transformer.

The transformer is 100% efficient.

i)
The size of the potential difference (voltage) across the secondary coil is

[1]

  ☐ A twice the size of the current in the primary coil
  ☐ B half the size of the current in the primary coil
  ☐ C twice the size of the voltage across the primary coil
  ☐ D half the size of the voltage across the primary coil

ii)
Explain how an alternating current in the primary coil causes an alternating current in the secondary coil of the transformer.

[3]

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3a3 marks
Complete the following sentences using one of the phrases from the box below.
 
 
efficiency is reduced
the national grid
a power station
heat loss is reduced
a transformer

 

(i)
Electrical power is generated at ..........................................................

[1]

(ii)
Electricity is transmitted over long distances by transmission lines that are part of
 
..........................................................

[1]

(iii)
Electricity is transmitted at high voltages so that ..........................................................
[1]

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3b1 mark
Which statement is true for transformers?


  ☐ A Transformers can only step-up voltages.
  ☐ B Transformers can only step-down voltages.
  ☐ C Transformers can work with direct current.
  ☐ D Transformers have primary and secondary coils.

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3c2 marks

In a small transformer

  • the primary voltage is 230 V
  • the primary current is 0.020 A
  • the secondary voltage is 5.0 V

Calculate the secondary current.

Use the equation

I subscript s equals fraction numerator V subscript p cross times I subscript p over denominator V subscript s end fraction

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