A coil having $n$ turns and resistance $\mathrm{R\Omega }$ is connected with a galvanometer of resistance $4\mathrm{R\Omega }.$ This combination is moved in $t$ sec from a magnetic field $W_{1}wb$ to $W_{2}wb$. The induced current in the circuit is

In a uniform magnetic field of inductance $B$, a wire in the form of semicircular of radius $r$ rotates about the diameter of the circle with angular frequency $\omega$. If the total resistance of the circuit is $R$, the mean power generated per period of rotation is

The emf induced in the wire is. A small piece of metal wire is dragged across the gap between the poles of a magnet in $0.4 \mathrm{s}$. If the change in magnetic flux in the wire is $8\times {10}^{-4} \mathrm{Wb}$.

In $0.1 \mathrm{s}$, the current in a coil increases from $1 \mathrm{A}$ to $1.5 \mathrm{A}$. If inductance of coil is $60 \mathrm{mH}$, then induced current in the external resistance of $3\mathrm{\Omega }$ will be

The peak value of the induced emf is (in volts). A rectangular coil of $300$ turns has an average area of $25 \mathrm{cm}\times 10 \mathrm{cm}$. The coil rotates with a speed of $50 \mathrm{cps}$ in uniform magnetic field of strength $4\times {10}^{-2} \mathrm{T}$ about an axis perpendicular to the field.

A $50 \mathrm{mH}$ coil carries a current of $2 \mathrm{A}$, the energy stored in joule is