Question

An e.m.f. is induced in a coil when ................. linked with it changes.

Answer 1

An emt is induced in a coil when flun linked with its changes.If a coil is placed in a magnetic field then the flux linked with the coil is the scalar product of the magnetic field intensity vector and the area vector of the coil.

Hence flux $\overrightarrow{B}.\overrightarrow{A}$

Where $\overrightarrow{B}$ = mag.field intensity

$\overrightarrow{A}$ = area vector of the coil

and the emf induced is the rate of change of flux

i.e. $ϵ=\frac{dQ}{dt}$

where $ϵ=e.m.f$

In an $AC$ generator ,maximum number of lines of force pass through the coil when the angle between the plane of coil and lines of force is ${90}^0$.

Working: When the conductor loops attached on the iron core rotates inside the magnetic field, emf is induced across its arm and hence current is generated, as the flux linked with the loop changes sinusoidally.

$ϵ=\frac{dQ}{dt}$ $ϵ$ =emf induced

$Q$=flux linked in loop