# What is Electromagnetic Induction ?

Electromagnetic Induction:

Whenever the magnetic flux linked with a coil (or a closed circuit) changes with time, an emf and a current are induced in the circuit. This phenomenon first observed by Faraday is called electromagnetic induction.

Magnetic flux :

Magnetic flux associated with any area is given by the expression

$\large d\phi_B = \vec{B}.\vec{ds}$

$\large \phi_B = \int \vec{B}.\vec{ds}$

Here $\vec{B}$ is the magnetic field and $\vec{ds}$ is area element. Area is taken as a vector quantity and its direction is perpendicular to surface

Magnetic Flux associated with plane coil having N turns in a uniform magnetic field $\vec{B}$  is equal to

$\large \phi_B = N ( \vec{B}.\vec{A} )$

$\large \phi_B = N B A cos\theta$

Here N is the number of turns in the loop

B = magnetic field strength

A = area of the loop

θ = angle between area vector and magnetic field.