# (Chapter 7) Magnetism and Electromagnetism

How can you tell if a material is magnetic? Which metals are magnetic?
If it can repel another magnet. Iron, steel, cobalt and nickel are all magnetic.
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What is a magnetic field?
The area around a magnet in which a magnetic force is acting, it comes out of the south and goes in the north pole.
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What is a permanent magnet? An induced magnet?
A permanent magnet produces its own magnetic field, it always has a north and a south pole. An induced magnet only becomes magnetic when placed in a magnetic field.
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What is flux density?
The number of magnetic field lines in a given area.
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How do you calculate the force on a wire?
F=BIL, Force (N) = Magnetic Flux Density (T) x Current (A) x Length (m)
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What is the left hand rule?
thuMb: Movement, First finger: Field, seCond finger: Current.
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What is induced potential? How does it happen?
The potential difference produced by a wire as it is moved across a magnetic field, this happens as it is breakig magnetic field lines which pushes electrons along the wire.
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What is induced current?
If a wire is part of a complete circuit, the potential difference will cause a current in the circuit.
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How does an electric motor work?
See diagram
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How does a moving-coil loudspeaker work?
See diagram
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How do you increase the magnetic fireld of a solenoid?
Using a larger current, using more turns of wire, putting the turns closer together and putting a soft iron core through the centre.
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How does a car motor battery work?
Igniton switch turned > Iron core becomes magnetised > A current flows through solenoid > Motor is connected to the battery > Solenoid moves to connect to the contacts > Engine is fully connected.
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## Other cards in this set

### Card 2

#### Front

What is a magnetic field?

#### Back

The area around a magnet in which a magnetic force is acting, it comes out of the south and goes in the north pole.

### Card 3

#### Front

What is a permanent magnet? An induced magnet?

### Card 4

#### Front

What is flux density?

### Card 5

#### Front

How do you calculate the force on a wire?