Induction and AC current

• Principle for Lenzs law

  Conservation of energy
• Faradays law


  The magnitude of an induced EMF is directly proportional to the rate of change of flux linkage
• One electron is in a uniform electric field, one in a magnetic field, both at 90 degrees to field lines, whats their motion

  • In the electric field the electron will experience an attractive force and accelerate towards the positive plate in a parabolic motion
  • In the magnetic field the electron will experience an attractive force and accelerate in circular motion
• Magnetic flux


  It is the total component of the magnetic flux density passing at right angles through a surface of area A
• Flux on a field line diagram

  The total number of field lines passing through the object/surface

  • the arrows will point from north to south
• One stationary electron is placed in a uniform electric field and one in a magnetic field what will the motion be

  • In the electric field the electron will experience an attractive force and accelerate towards the positive plate
  • In the magnetic field the electron will experience zero force and remain stationary
• Eddy current in a transformer

  A current induced by changing the flux within the core
• Use of a laminated core in a transformer is to

  Reduce the heating effect of induced eddy currents
• Other tesla units


  Wb m^-2 or N m^-1 A^-1
• One electron is in a uniform electric field, another in a magnetic field, both moving along field lines, what will their motion be

  • In the electric field the electron will experience an attractive force and accelerate towards the positive plate
  • In the magnetic field the electron will experience zero force and move at a constant velocity
• Lenzs law


  The direction of an induced EMF or current is always in such a direction as to oppose the change that caused it