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  Electromagnets

1.        In the lesson you have investigated some factors about electromagnets. You have carried out 3 experiments to investigate these factors. each experiment was carefully controlled to make it a fair test.

Copy out the table below into your books and complete it to show how each experiment was made fair. The first one has been done for you.

Experiment

How the experiment was made fair

1. The effect of changing the core material on the strength of the electromagnet

 

a) Each core was the same size

b) Each core had the same number of coils

c) The current was kept the same each time

2. The effect of changing the number of coils on the strength of the electromagnet

 

a)

b)

3. The effect of changing the current flowing in the coils on the strength of the electromagnet

 

a)

b)

 

2.       Each experiment had an effect on the strength of the electromagnet. Copy and complete each sentence

a)       Only one core material became an electromagnet. This core material was ____________.

b)       When the number of coils on the electromagnet was _______________ the strength of the electromagnet ______________

c)       When the current flowing through the coils of the electromagnet was _________ ........... (finish this sentence)

3.        A use for electromagnets is in scrap yards for picking up old cars and putting them where you want them. We only use iron in electromagnets and not steel. Look at the sentences below and decide which is the best reason for not using steel

a)       Steel goes rusty, iron does not.

b)       Steel stays magnetic when the current in the coils turns off

c)       Steel is much stronger than iron

4.        Explain your answer to question 3.