Generation of Electricity

Teacher demonstration Inducing an electric current

Teacher demonstration - Dynamo

Electromagnetic induction What will happen if you move a magnet into a coil of wire? A current is induced in the coil. Only when the magnet is moving.

Stationery magnet What happens when the magnet is in the coil? Nothing!! A current is only induced when the magnet is moving.

Electromagnetic induction What will happen if you move the magnet out of the coil of wire? A current is induced in the coil. This time in the opposite direction. If you reverse the direction of the movement, then you reverse the direction of the current.

Electromagnetic induction When you move a magnet in a c______ an electric current is induced The direction of the induced current is reversed if… 1)The magnet is moved in the opposite d________ 2)The other pole is inserted f______ 3)Thus an A________ Current (AC) is induced The size of the induced current can be increased by: 1)I ________ the speed of movement 2)Increasing the m________ strength 3)Increasing the number of c_______

Michael Faraday is generally credited with having discovered electromagnetic induction. Electromagnetic induction Michael Faraday ( ) Dvd – generating electricity (4mins) Moving a wire through magnetic field lines induces a voltage. If the wire is stationery nothing happens. If the wire moves along the magnetic field lines (without cutting them) nothing happens.

Generator

The Electrical Generator Run the animation to see the display of the electrical output for the generator... Generators produce an alternating current (AC).

Current Time + - AC is alternating current, a current which is constantly changing in direction. Source of AC? Mains electricity (50Hz)

DC is direct current, current that is always flowing in one direction. Sources of DC? Cells or batteries Current Time + -

Bicycle dynamo At the bottom of the dynamo there is a coil. Above the coil there is a magnet. The magnet and the coil do not touch. A magnet is connected to a driving wheel which touches the tyre. So when the wheel is turning, so is the magnet. When the magnet is turning in side the coil a current is induced which lights the bulb in the lamp. coil magnet