# GCSE physics unit 3 part 1

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• Created by: tory
• Created on: 17-01-11 15:04

THE MOTOR EFFECTt:

In the motor effect, the force:

Key Points:

1) Is increased if the current or the strength of the magnetic field is increased

2) Is at right angles to both the direction of magnetic field and to the wire

3) Is reversed if the direction of either the current or the magnetic field is reversed.

The force is maximum if the wire is at an angle of 90 degrees to the magnetic field, and zero if the wire is parallel to the magnetic field.

When a current passes through a coil, the coil spins because:

• A force acts on each side of the coil due to the motor effect
• The force on one side of the coil is in the opposite direction to the force on the other side.
• The split ring commutator reverses the direction of the current around the coil every half turn. Because the sides swap over each half-turn, the coil is always pushed in the same direction

ELECTROMAGNETIC INDUCTION:

Key Points:

1) When a wire cuts the magnetic field lines, a potential difference (p.d) is induced in the wire

2) If the wire is part of a complete circuit, the induced p.d causes a current in the circuit

3) The size of the current is increased if the wire moves faster, or if a stronger magnet is used

The size of the induced p.d is increased by increasing

• The speed…

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