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Faraday's Law of Induction

Also known as electromagnetic induction · induced EMF

ε=NΔΦΔt\varepsilon = N \frac{\Delta\Phi}{\Delta t}
sig figs

Worked example: 500 turns, 2 mWb in 0.1 s → emf = 10 V. Press Try an example to run it live, then adjust anything.

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See also

EMF Induced in a Coupled Coil: Both use induced EMF and time interval.Magnetic Field of a Solenoid: Both use number of turns.Motional EMF (ε = BLv): Both use induced EMF.
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Faraday's Law of Induction explained

εΔΦΔtN

Faraday's 1831 discovery is the bridge between mechanics and electricity: change the flux through a coil and a voltage appears, one volt per weber-per-second per turn. The N multiplies because each turn is a voltage source in series: the reason transformers and generators are wound with hundreds of turns. Sweep a magnet that changes flux by 2 mWb through a 500-turn coil in 0.1 s and you induce 10 V.

The full law carries a minus sign (Lenz's law): the induced current always opposes the change that created it, nature's built-in inertia against flux change, and the origin of eddy-current braking.

Faraday's Law of Induction formula

ε=NΔΦΔt\varepsilon = N \frac{\Delta\Phi}{\Delta t}
Where
  • ε\varepsilon= Induced EMF (V)
  • NN= Number of turns
  • ΔΦ\Delta\Phi= Flux change (Wb)
  • Δt\Delta t= Time interval (s)
Revised 16 October 2026
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formula.expert. (2026, October 16). Faraday's Law of Induction Formula & Calculator. https://formula.expert/solvers/faradays-law

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