Electromagnetic Induction

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Electromagnetic Induction

Published by: Zaya

Published date: 26 Jun 2021

Electromagnetic Induction in Grade 12 Physics

Electromagnetic Induction

Suppose while shopping you go cashless and your parents use cards. The shopkeeper always scans or swipes the card. The shopkeeper does not take a photo of the card or tap it. Why does he swipe/scan it? And how does this swiping deduct money from the card? This happens because of the ‘Electromagnetic Induction’.

Can moving objects produce electric currents? How to determine a relationship between electricity and magnetism? Can you imagine the scenario if there were no computers, no telephones, no electric lights? The experiments of Faraday have led to the generation of generators and transformers.

electromagnetic induction
The induction of an electromotive force by the motion of a conductor across a magnetic field or by a change in magnetic flux in a magnetic field is called ‘Electromagnetic Induction’.

This either happens when a conductor is set in a moving magnetic field (when utilizing an AC power source) or when a conductor is always moving in a stationary magnetic field.

This law of electromagnetic induction was found by Michael Faraday. He organized a leading wire according to the setup given underneath, connected to a gadget to gauge the voltage over the circuit. So when a bar magnet passes through the snaking, the voltage is measured in the circuit. The importance of this is a way of producing electrical energy in a circuit by using magnetic fields and not just batteries anymore. The machines like generators, transformers also motors work on the principle of electromagnetic induction.

Faraday’s law of Electromagnetic Induction

electromagnetic induction

  • First law: Whenever a conductor is placed in a varying magnetic field, EMF induces and this emf is called an induced emf, and if the conductor is a closed circuit then the induced current flows through it.
  • Second law: The magnitude of the induced EMF is equal to the rate of change of flux linkages.
    Based on his experiments we now have Faraday’s law of electromagnetic induction according to which the amount of voltage induced in a coil is proportional to the number of turns and the changing magnetic field of the coil.

So now, the induced voltage is as follows:

e = N × dΦdt


e is the induced voltage
N is the number of turns in the coil
Φ is the magnetic flux
t is the time