1. Electric Currents from Magnetism
17 - 3

2. Electromagnetic Induction
1831
Michael Faraday
A current can be produced by pushing a magnet through a coil of wire

3. Electromagnetic Induction
Moving a magnet in and out of a coil of wire
Causes a charges in wire to move

4. Faraday’s Law
An electric current can be produced in a circuit by a changing magnetic field

5. Loop of wire moving between two magnetic poles
As loop moves in and out – current induced
As wire moves in and out of field – current will continue

6. Rotating the current or changing the strength of magnetic field - Induces current

7. Energy from nothing? Conservation of energy
Pushing a loop through a magnetic field requires work
Greater the magnetic field – stronger the force required to push loop through field

8. Energy from nothing?
Electrical energy is produced by electromagnetic induction

9. Moving Electric Charges
Force at max value when charged particles move perpendicular to magnetic field.

10. Zero current when the wire moves parallel to magnetic field

11. Generators Convert mechanical energy to electrical energy
Expend energy to do work
Loop of wire inside turns within a magnetic field – current produced

12. For each ½ rotation of loop
Current produced by generator reverses direction
Alternating Current (AC)

13. Electromagnetic Waves
Oscillating electric and magnetic field
Perpendicular to each other
Perpendicular to wave direction

14. Step-Up Transformer
Increases voltage - output voltage is greater than the input voltage

15. # of wire turns on the secondary coil > # of turns on the primary coil

16. Step-Down Transformer
Decreases the voltage - output voltage is less than the input voltage

17. # of wire turns on the secondary coil < # of turns on the primary coil