Lenz’s Law of Electro Magnetic induction

What is Lenz’s Law ?

Earlier we know about Faraday’s Law in or previous topics.

In Faraday’s Law we learn When a conductor is placed in varying magnetic field an EMF is induced across the conductor. And if we closed the circuit induced current flows throgh it.

And According to Lenz Law, When EMF in induced according to Faraday’s law, the polarity of induced EMF is such that it opposses the cause it.

It means When Induced current in the coil, it creats its own own magnetic filed of opposite polarity (direction of this current can be found with Flamimg left hand rule) it opposses the change in magnetic filed which produced induced current.

And Current will flow in constant way.

If there is opposition according to Lenz Law . Induced current will make own magnetic in same direction and create a magnetic field.

Formula of Lenz’s Law

According to Faraday’s Law, when an EMF is generated by a change in magnetic flux the polarity of the induced EMF is such, that it produces an induced current whose magnetic field (Induced current in coil) opposes the initial changing magnetic field which produced it.

The negative sign will use in Faraday’s law of electromagnetic induction formula that indicates the induced EMF (ε) and the change in magnetic flux (δΦB) have opposite signs.

The formula for Lenz’s law is shown below:

ε=  -N ΔΦ/Δt


  1. ε = Induced EMF
  2. δΦB = change in magnetic flux
  3. N = No of turns in coil


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