Electromagnetism

• flemings left hand rule

  first finger - direction of magnetic field (N --> S)

  second finger - direction of current (+ --> -)

  thumb - direction of motion
• how to increase force in motor

  . more turns of wire

  . increased magnetic field

  . increase current
• purpose of a spilt ring in a motor

  used for reversing the direction of current in the coil.

  For continuous rotation of the coil in the same direction, current must be reversed
• purpose of carbon brushes in motor

  used to conduct electrical current between the stationary and rotating parts of a motor/ac generator
• factors affecting output of an a.c generating


  number of coils

  rate of coil rotation

  strength of magnetic field

  area of coil or iron core
• purpose of a slip ring in an a.c generator

  devices that allows the conduction of current from static to moving parts
• how does transformers work

  changing current in the primary coil sets up a changing magnetic field in the primary coil which induces a voltage in the secondary coil
• why is the core of a transformer laminated

  reduces energy loss due to eddy currents