1. This is a little summary note on electromagnets

2. BASIC PRINCIPLE
When electricity flows in a wire a magnetic field is formed around the wire.
The stronger the current the stronger the magnetic field will be.
When a current stops flowing there is no magnetic field

3. HOW WE CAN MAKE A STRONGER MAGNETIC EFFECT
If we make a coil of wire called a solenoid the combined effect of the magnetic field around each wire results in a bar magnet being created.
The more coils the stronger the combined magnetic field

4. MAKING AN ELECTROMAGNET
If we put a soft iron core inside the solenoid when a current flows an electromagnet is formed

5. STRENGTH INCREASES IF IT HAS:
More coils
More current
A bigger iron core

6. How it works
Current goes on
Electromagnet is formed
Armature is pulled towards the magnet
This closes the contacts
So the mains circuit is complete
So the motor goes on

7. Quick quiz to test yourself
How do you make an electromagnet?
What is a solenoid?
What will happen to the strength of an electromagnet if:
You add another battery?
You increase the number of coils around the iron core?
You used an aluminium core instead of a soft iron one?
You used a smaller iron core?
How would you design a fair test to test the effect of adding more coils?

8. Need more revision?
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