$A$ non-conducting ring (of mass $m$,radius $r$,having charge $Q$) is placed on a rough horizontal surface in a region with a transverse magnetic field. The magnetic field is increasing with time at a rate $R = dB/dt$. If the coefficient of friction between the surface and the ring is $\mu$,for the ring to remain in equilibrium,$\mu$ should be greater than:

$A$ conducting ring of radius $r$ is placed in a varying magnetic field perpendicular to the plane of the ring. If the rate at which the magnetic field varies is $x$,the electric field intensity at any point on the ring is:

In the branch $AB$ of a circuit,as shown in the figure,a current $I = (t + 2) \ A$ is flowing,where $t$ is the time in seconds. At $t = 0$,the value of $(V_A - V_B)$ will be: (in $V$)

$A$ long solenoid of radius $R$ carries a time $(t)$-dependent current $I(t) = I_{0} t(1-t)$. $A$ ring of radius $2R$ is placed coaxially near its middle. During the time interval $0 \leq t \leq 1$,the induced current $(I_{R})$ and the induced $EMF$ $(V_{R})$ in the ring change as

$A$ rectangular wire loop of sides $8 \; cm$ and $2 \; cm$ with a small cut is moving out of a region of uniform magnetic field of magnitude $0.3 \; T$ directed normal to the loop. Suppose the loop is stationary but the current feeding the electromagnet that produces the magnetic field is gradually reduced so that the field decreases from its initial value of $0.3 \; T$ at the rate of $0.02 \; T \, s^{-1}$. If the cut is joined and the loop has a resistance of $1.6 \; \Omega$,how much power is dissipated by the loop as heat? What is the source of this power?

$A$ conducting circular loop made of a thin wire has an area of $3.5 \times 10^{-3} \, m^2$ and a resistance of $10 \, \Omega$. It is placed perpendicular to a time-dependent magnetic field $B(t) = (0.4 \, T) \sin(50 \pi t)$. The field is uniform in space. The net charge flowing through the loop during the interval $t = 0 \, s$ to $t = 10 \, ms$ is close to.......$\mu C$.