$A$ magnetic field $4 \times 10^{-2} \, T$ acts at right angles to a coil of area $100 \, cm^2$ with $50$ turns. The average e.m.f. induced in the coil is $0.1 \, V$, when it is removed from the field in time '$t$'. The value of '$t$' is

$A$ conducting loop of radius $10/\sqrt{\pi}$ $cm$ is placed perpendicular to a uniform magnetic field of $0.5$ $T$. The magnetic field is decreased to zero in $0.5$ $s$ at a steady rate. The induced emf in the circular loop at $0.25$ $s$ is (in $mV$)

$A$ coil has an area of $0.05\,m^2$ and it has $800\,turns$. It is placed perpendicularly in a magnetic field of strength $4 \times 10^{-5}\,Wb/m^2$. It is rotated through $90^o$ in $0.1\,s$. The average emf induced in the coil is ........... $V.$

$A$ coil having $500$ square loops each of side $10 \ cm$ is placed normal to a magnetic flux which increases at a rate of $1 \ T s^{-1}$. The induced emf is (in $V$)

$A$ circular coil of radius $10 \; cm$, $500$ turns, and resistance $2 \; \Omega$ is placed with its plane perpendicular to the horizontal component of the earth's magnetic field. It is rotated about its vertical diameter through $180^{\circ}$ in $0.25 \; s$. The induced e.m.f. in the coil is (Take $B_H = 3.0 \times 10^{-5} \; T$).

The figure shows a conducting loop placed in a magnetic field. The magnetic flux through the loop changes according to the equation $\phi = 5t - 10t^2$. What is the direction and magnitude of the induced current at $t = 0.25\, s$?