# Motors, Generators & Transformers

Information on how generators, motors and transformers work.. :)

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HOW A MOTOR WORKS ­ Motor effect
A coil is inside the magnetic field which is produced by the magnets
When a current flows through the coil is experiences a force due to the magnetic field
There is a downwards force on one side of the coil and an upwards force on the other side
So the coil turns around the axle
When the coil is vertical the brushes are not in contact and the current stops
The coil keeps moving until brushes make contact and then the coil is reversed
The coil continues to turn in the same direction
MOTOR = split ring ­ If a motor had a slip ring the coil won't
turn as current will always be in the same direction.
A split ring creates different currents
Factors affecting size of force ­
Size of current
Size of magnetic field (weak or strong)
Factors affecting direction of force ­
Changing the poles
Direction of the current
ELECTROMAGNETIC INDUCTION ­ Generator effect
How a generator works...
The rotating coil cuts through the magnetic field
This induces a p.d across the ends of the coil
There is a complete circuit so an induced current flows through the wire/ the component (lamp etc)
As the coil turns the direction of the current changes every half turn
Therefore the current is A.C
The slip rings rotate with the coil
And the brushes connect the slip rings to the circuit
Otherwise the wires would tangle
If the direction of motion or the polarity of the magnet is changed the induced p.d and direction of
induced current is reversed.

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TRANSFORMERS
Primary coil is connected to an A.C supply ­ There is a changing magnetic field
(Not a direct current because the magnetic field is then not a changing magnetic field)
Iron core = MAGNETIC
Points for how a transformer works ­
- Type of current and affect on primary coil
- Affect on iron core
- Affect on secondary coil
How they work ­
There is an alternating current through the primary coil