Lenz law is consequence of the law of conservation of:

Concept:

• Lenz's Law: This law states that the induced emf in a conductor due to a changing magnetic field is such that the magnetic field created by the induced emf opposes the change in a magnetic field.

     -----(1)

Where Emf is the induced voltage (also known as electromotive force), N is the number of loops, Δϕ Change in magnetic flux, Δt Change in time.

Explanation:

• In the above experiment when the N-pole of the magnet is moved towards the coil 
• Thus work has to be done against the force of repulsion in bringing the magnets close
• When the N pole of the magnet is moved away, the south pole develops on the right face of the coil.
• Therefore work has to be done in this case.
• This mechanical work in moving the magnet changes into electrical energy producing induced current.

Hence energy transformation takes place. We can say that the law is a consequence of the conservation of energy.

Important Points 

•  A few applications of Lenz’s law are:
  • Eddy current balances
  • Metal detectors
  • Eddy current dynamometers
  • Braking systems on train
  • AC generators
  • Card readers
  • Microphones