generator effect / electromagnetic induction

what is the generator effect?

• coil of wire moved into magnetic field

• magnet moved into coil of wire

creates a potential difference in conductor and current (if part of a complete circuit)

how can the potential difference or current be reversed?

• magnet or conductor moved in opposite direction

• polarity reversed

how will the induced potential difference or current increase?

• speed of movement increases

  • cutting more magnetic field lines in a given time

• magnetic field strength increases

• number of turns on the coil increases

how do alternators (used in cars) generate alternating current?

1. rotate coil in magnetic field

   • or rotate magnet in coil

2. coil/magnet spins = current induced in coil

   • current changes direction every half-turn

3. slip rings and brushes prevent contacts swapping every half turn

how do dynamos generate direct current?

1. rotate coil in magnetic field

   • or rotate magnet in coil

2. coil/magnet spins = current induced in coil

   • current changes direction every half-turn

3. split-ring commutators swap connection every half turn

   • keep current flowing in same direction