PYQ NEET- More Applications Of Amperes Law

Question 1

The answer is (B).

The magnetic flux linked with the coil is given by:

$\Phi = BA$

where $B$ is the magnetic field and $A$ is the area of the coil.

In this case, the plane of the coil is perpendicular to the direction of the field, so the magnetic flux is:

$\Phi = BA = BR^2$

Question 2

The answer is (C).

The magnitude of the induced emf in the loop is given by:

$\epsilon = \frac{d\Phi}{dt}$

where $\Phi$ is the magnetic flux and $t$ is time.

In this case, the magnetic flux changes from $BA$ to $-BA$ when the loop is turned through 180° about a diagonal. So the magnitude of the induced emf is:

$\epsilon = \frac{d\Phi}{dt} = \frac{2BA}{t} = 2BRa^2$