Lenz's law isconsequence of the law of conservation of [JIPMER 1997; CPMT 1990; RPMT 1997; MP PET 1999; MP PMT 2000, 03; RPET 2003; AFMC 2004]

Lenz’s law is a consequence of the law of conservation of energy.

Lenz’s law

Lenz’s law states that induced electromotive force with different polarities induces a current whose magnetic field opposes the change in magnetic flux through the loop in order to ensure that original flux is maintained through the loop when current flows in it.


  • According to Lenz’s law, the induced EMF always opposed the cause which is producing it.
  • If the cause of the induced EMF is a time-varying current, then the induced EMF opposes the changes in current and maintaining status quo.
  • If the cause is the growth of current in the loop then, the induced EMF establishes a current in opposite direction opposing the cause. Similarly, if the cause of induced EMF is decay in the current then the induced EMF establishes a current in the original current direction, Thus again opposing the growth. Thus, Lenz’s law is in accordance with the law of conservation of energy principle.

The energy of the field increases with the magnitude of the field. Lenz’s law infers that there is an opposite-field created due to an increase or decrease of magnetic flux around a conductor so as to hold the law of conservation of energy.

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