# Physics P7

• Created by: abbiedye
• Created on: 29-07-18 21:25

## How do compasses show the direction of magnetic fi

• You can move a compass around a magnet and trace its position on some paper to build up a picture of what the magnetic field looks like
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## Difference between permanent and induced magnets

• Permanent magnets produce their own magnetic field
• Induced magnets are magnetic materials that turn into a magnet when they're put into a magnetic field
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## What is the right-hand thumb rule?

• Using your right hand, point your thumb in the direction of the current and curl your fingers
• The direction of your fingers is the direction of the field
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## What is a solenoid?

• You can increase the strength of the magnetic field that a wire produces by wrapping the wire into a coil called a solenoid
• This happens because the field lines around each loop of wire line up with each other
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## What is the motor effect?

• When a current-carrying wire (or any other conductor) is put magnetic poles, the magnetic field around the wire interacts with the magnetic field it has been placed in. This causes the magnet and the conductor to exert a force on each other
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## How do you calculate the size of the force?

• force = magnetic flux density x current x length
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## What is Fleming's left-hand rule?

• Using your left hand, point your first finger in the direction of the magnetic field
• Point your second finger in the direction of the current
• Your thumb will then point in the direction of the force
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