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GCSE Level Questions: Magnets and Electromagnets

Q2.

(a) Electromagnets are often used at recycling centres to separate some types of metals from other materials. Give one reason why an electromagnet would be used rather than a permanent magnet.

An electromagnet can be switched off so it will release an object, whereas a permanent can't be made to just 'release' the object it has picked up .

OR an electromagnet can be made to be extremely powerful - more powerful than a permanent one.

[1 mark]

(b) Some students want to build an electromagnet. The students have the equipment shown below:

Describe how the students could build an electromagnet. Include in your answer how the students should vary and test the strength of their electromagnet.

This type of question is marked in two ways:

- the examiner looks for relevant points

- but also for a logical sequence...

It is not just a 'tick fest' - but a marker does look to see how many relevant points you have made, then considers how you have strung them together to put your answer into a 'level'

Level 3:

There is a description of:

how the electromagnet is made
and
how the strength of the electromagnet can be varied
and
how the strength of the electromagnet can be tested
5 - 6 marks
Level 2:

There is a description of how the electromagnet is made
and either there is a description of

how the strength of the electromagnet can be varied
or
how the electromagnet can be tested
3 - 4 marks
Level 1:

There is a basic description of

how to make an electromagnet
or
how the strength of the electromagnet can be varied
or
how the electromagnet can be tested
1 - 2 marks
Level 0:

No relevant information
0 marks

 

Examples of points that should be made in the response:


Details of how to make an electromagnet

wrap the wire around the nail
connect the wire to the power supply (with connecting leads and croc clips)
switch on the power supply - or say, a current should be sent along the wire


Details of how to vary the strength of the electromagnet

change the number of turns (on the coil)
change the current (through the coil) or change the potential difference (across the coil)
change the separation of the turns or wrap the coil more tightly


Details of how to test the electromagnet

suspend paperclips from the electromagnet
the more paperclips suspended, the stronger the electromagnet is
clamp the electromagnet at different distances from the paperclip(s)
the further the distance from which paperclips can be attracted the stronger the electromagnet is
test before and after making alterations to change the strength

count the number of paperclips with different current or p.d. or no. of turns or core and see if the number changes/increases
compare the results from before and after making alterations
use de-magnetised paper clips

[6 marks]

(TOTAL 7 marks)