Question

A time-varying magnetic field is caused by which of the following?

Answer 1

A time-varying magnetic field can be caused by fluctuating electric fields.

Answer 2

Answer:

-fluctuating electric fields

Explanation:

As we know that electric field and magnetic field is related by the equation given as

$\int E. dl = -\frac{d\phi}{dt}$

here we know that

$\phi = B.A$

now we have magnetic field is time varying

$\int E.dl = -A\frac{dB}{dt}$

now for closed loop of radius "r" we will have

$E(2\pi r) = - A\frac{dB}{dt}$

$E = -\frac{A}{2\pi r}\frac{dB}{dt}$

so here this produce electric field as per above formula and it is also known as non conservative electric field.