12.6 Electromagnetic Induction How Voltage is Created!

1831 Michael Faraday English Joseph Henry American

Voltage is induced by the motion Electric current is produced by moving a magnet into or out of a wire coil Voltage is induced by the motion Induced = caused by

Doesn’t matter if the magnet moves

Or if the wire moves

Increase the number of coils – increase the voltage produced

Nothing is Free Work is done because the induced current in the loop creates a magnetic field which repels the approaching magnet. More coils – harder to produce

The amount of current depends on how quickly the magnetic field lines are traversed by the magnet Very slow – hardly any voltage Quick – much greater voltage

Electromagnetic Induction Inducing voltage by changing the magnetic field around a conductor

Faraday’s Law The induced voltage in a coil is proportional to the number of loops multiplied by the rate at which the magnetic field changes within those loops.

Amount of Current Also depends on Resistance in the coil Resistance in the circuit

Where is electromagnetic induction used? Drop Zone Great America

Traffic Lights When the iron parts move over the coils, the Earth’s magnetic field in the coils in changed – changing the light.

Traffic Lights

Security Gates Any metal you carry changes the magnetic field This induces voltages ALARM sounds

Magnetic Strips on Cards Induced voltage identify the card