WJEC GCSE Physics 3 Generating and Transforming Electricity

Electricity.. :)

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  • Created on: 22-05-12 18:14
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Megan Nolan
Triple Physics Revision Notes:
Electromagnetic Induction
Electromagnets:
Any magnet has an electric field around it which is
strongest at its poles; the arrows showing current will
always point from North to South.
Electromagnets are more useful as you can turn the
magnetic force on and off, the strength can be changed,
and they can be made cheaply into a variety of shapes.
E.g. They are used in car yards to lift the car.
When a wire cuts through a
magnetic field/ flux, it induces
(causes) a current to flow. If a
magnetic field moves past a wire,
the same thing happens (flux is cut
and current induced).
Generators:
A magnet that spins inside a coild of wire or a coil of wire that spins inside a magnetic field and cuts
the flux generates a current.
To get a better and stronger generator, you could;
Increase the number of coils
Use a magnet with a stronger magnetic field
Spin the magnet or the wire faster
Use a magnet with a circular magnetic field (so the field covers a greater distance)
Flemming's Right Hand Rule:
This can be used to predict current
flow as all three (motion, field and
current) act at 90o angles from
each other.
Movement- Thumb
Field- First finger
Current- Second Finger
Transformers:

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Megan Nolan
Transformers are used to step up or step down the voltage of a power supply. Before the power is
released onto the national grid, the voltage
must be increased (meaning the current will
decrease) to increase the efficiency. The
voltage is stepped down again before
entering houses or factories.
Alternating current must be used in order to
step up or down electricity.
As the voltage increases, the current
decreases.…read more

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