magnetism 2

• electric motor

  • coil rotate: opp current -> opp motor effect
  • split-ring commutator rotate w/ coil
  • every half turn - swap site contact brush - swap DC direction
  • same direction: turning F acting on coil same (current of wires close to N/S same)
• induce electromagnetism

  • induce emf, current -> create 2nd magnetic field
  • this oppose change that cause it

  reverses if reverse polarity (of 1st magn field) and emf (2nd)
• AC generator

  • coil turns -> induce emf, current (electromagnetism)
  • slip ring rotates with coil. it doesnt swap, its in continuous contact with brush so current flow continuously
  • every half turn: induced current change direction
  • -> generate AC current
• AC generator volt output

  • parallel to field line - cut at fastest rate
  • perpendicular (halfturn) - 0 volt output as not cut thru field lines