One turn of insulated wire in the form of a planar square frame with side $l = 0.2\,m$ and resistance $1\,\Omega$ is placed in a uniform magnetic field perpendicular to the plane of the frame. The current passing through the turn when the magnetic field starts to decrease at a constant rate of $0.1\,T/s$ is....$mA$

At time $t=0$, a magnetic field of $1000 \; \text{Gauss}$ is passing perpendicularly through the area defined by the closed loop shown in the figure. If the magnetic field reduces linearly to $500 \; \text{Gauss}$ in the next $5 \; \text{s}$, then the induced $EMF$ in the loop is ........ $\mu \text{V}$.

$A$ non-conducting ring of radius $R$ and mass $m$ having charge $q$ uniformly distributed over its circumference is placed on a rough horizontal surface. $A$ vertical time-varying uniform magnetic field $B = 4t^2$ is switched on at time $t=0$. The coefficient of friction between the ring and the table,if the ring starts rotating at $t = 2 \, s$,is:

$A$ square loop of side $2.0\,cm$ is placed inside a long solenoid that has $50$ turns per centimetre and carries a sinusoidally varying current of amplitude $2.5\,A$ and angular frequency $700\,rad\,s^{-1}$. The central axes of the loop and solenoid coincide. The amplitude of the emf induced in the loop is $x \times 10^{-4}\,V$. The value of $x$ is $.........$ (Take $\pi = \frac{22}{7}$)

$A$ point charge $Q$ is moving in a circular orbit of radius $R$ in the $x$-$y$ plane with an angular velocity $\omega$. This can be considered as equivalent to a loop carrying a steady current $I = \frac{Q\omega}{2\pi}$. $A$ uniform magnetic field along the positive $z$-axis is now switched on,which increases at a constant rate from $0$ to $B$ in one second. Assume that the radius of the orbit remains constant. The application of the magnetic field induces an emf in the orbit. The induced emf is defined as the work done by an induced electric field in moving a unit positive charge around a closed loop. It is known that,for an orbiting charge,the magnetic dipole moment is proportional to the angular momentum with a proportionality constant $\gamma$.
$1.$ The magnitude of the induced electric field in the orbit at any instant of time during the time interval of the magnetic field change is:
$(A)$ $\frac{BR}{4}$ $(B)$ $\frac{BR}{2}$ $(C)$ $BR$ $(D)$ $2BR$
$2.$ The change in the magnetic dipole moment associated with the orbit,at the end of the time interval of the magnetic field change,is:
$(A)$ $-\gamma BQR^2$ $(B)$ $-\gamma \frac{BQR^2}{2}$ $(C)$ $\gamma \frac{BQR^2}{2}$ $(D)$ $\gamma BQR^2$
Give the answer for question $1$ and $2$.

The figure shows a circular area of radius $R$ where a uniform magnetic field $\vec B$ is directed into the plane of the paper and is increasing in magnitude at a constant rate. In this case,which of the following graphs,drawn schematically,correctly shows the variation of the induced electric field $E(r)$ with distance $r$ from the center?