1. 12.6 Electromagnetic Induction
How Voltage is Created!

2. 1831
Michael Faraday
English
Joseph Henry
American

3. 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

4. Doesn’t matter if the magnet moves

5. Or if the wire moves

6. Increase the number of coils – increase the voltage produced

7. 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

8. 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

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

10. 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.

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

12. Where is electromagnetic induction used?
Drop Zone
Great America

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

14. Traffic Lights

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

16. Magnetic Strips on Cards
Induced voltage identify the card