# Why a change in magnetic flux gives rise to induced EMF?

## Question:

Why a change in magnetic flux gives rise to induced EMF?

As discovered by Faraday and Lenz, in a conductive material where the flux of the magnetic field that passes through it varies, an electromotive force (potential difference) capable of performing work will appear. This is known as the principle of electromagnetic induction and is one of the fundamental bases of electromagnetism.

The mathematical expression that relates the electromotive force to the variation of the magnetic field flux is known as the Faraday-Lenz law:

{eq}\varepsilon =-\frac{\mathrm{d}\Phi_B}{\mathrm{d}t} {/eq}

The real key to what happens is contained in the minus sign of this equation. This sign was introduced in the equation by Lenz after it was formulated by Faraday. When the flux of the magnetic field that passes through the material varies, an electric current will appear that will generate a magnetic field that will offset the variation in the flux of the external magnetic field that is taking place. In other words, the material will try to maintain its initial state. It is important to clarify that the material does not have to be solid, it can be a closed loop of conductive wire as well, in this case the current will circulate throughout the spiral. Thanks to this phenomenon we can enjoy of the electric current in our homes.