Electric Currents from Magnetism 17 - 3

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

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

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

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

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

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

Energy from nothing? Electrical energy is produced by electromagnetic induction

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

Zero current when the wire moves parallel to magnetic field

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

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

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

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

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

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

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