Question

Briefly explain the change in flux due to rate of change of area?

Answer 1

Magnetic flux

1. The total number of magnetic field lines passing through a given coil or area is referred to as magnetic flux.
2. It is the component of the magnetic field that passes through the coil that is shared by all.
3. Magnetic flux is represented by the symbol$B$, where $B$ is a magnetic field and the unit is Weber ($Wb$).
4. The magnetic flux value is a vector quantity that depends on the magnetic field direction.
5. Magnetic flux formula is given by:${\varphi }_B=BA\cos \theta$

Where,

${\varphi }_B$ is the magnetic flux.

$B$is the magnetic field

$A$ is the area

$\theta$ the angle at which the field lines pass through the given surface area

Rate of change of magnetic flux due to rate of change of area

According to Faraday’s second law of electromagnetic induction, we know that the induced emf in a coil is equal to the rate of change of flux linkage. Therefore,

$E=\frac{-d\varphi }{dt}$ where $\varphi =B.A$ , here $A$ is very small area.

So, $E=-B\frac{dA}{dt}-A\frac{dB}{dt}$

The first term is called motional emf because it is connected with area change, i.e., movement of the loop periphery.