# Faraday's Law of Induction **The electromotive force induced in a closed circuit is equal to the negative rate of change of magnetic flux through the circuit.** ![[Faraday'sLawOfInduction.svg|300]] *Faraday's law of induction; the left-hand rule can be used to identify the induced direction of current with the thumb pointing in the direction of the changing magnetic flux* > [!Example] Faraday's Law of Induction > *Faraday's law of induction*, also known as the *Faraday-Lenz law*, states that the electromotive force around a closed path is equal to the negative time rate of change of the [[magnetic flux]] enclosed by the path. > > $\varepsilon=-\frac{d\Phi_{B}}{dt}$ > - $\varepsilon$ - *electromotive force*, $\text{V}$ > - $\Phi_{B}$ - *[[magnetic flux]]*, $\text{Wb}$ The negative sign simply indicates that the direction of the electromotive force opposes the change in magnetic flux, as described by [[Lenz's law]]. > If there are *several* connected closed paths in the form of a *tightly wound coil* of wire, then the law of induction states that > $\varepsilon=-N\frac{d\Phi_{B}}{dt}$ > - $N$ - *number* of turns of wire.