$A$ coil having an area $A_0$ is placed in a magnetic field which changes from $B_0$ to $4B_0$ in a time interval $t$. The $e.m.f.$ induced in the coil will be

Whenever a magnet is moved towards or away from a conducting coil,and an e.m.f. is induced,the magnitude of which is independent of:

$A$ conducting coil having $500$ turns has a cross-sectional area of $0.15 \ m^2$. $A$ magnetic field of strength $0.2 \ T$ linked perpendicular to this area changes to $1.0 \ T$ in $0.4 \ s$. The induced emf produced in the coil will be . . . . . . $V$.

$A$ magnetic field $B$ is confined to a region $r \le a$ and points out of the paper (the $z$-axis),$r = 0$ being the centre of the circular region. $A$ charged ring (charge $= Q$) of radius $b$,$b > a$ and mass $m$ lies in the $xy$-plane with its centre at the origin. The ring is free to rotate and is at rest. The magnetic field is brought to zero in time $\Delta t$. Find the angular velocity $\omega$ of the ring after the field vanishes.

Two square wire frames $abcd$ and $efgh$ are placed in a uniformly decreasing magnetic field as shown in the figure. The direction of the induced current in both the loops is

$A$ square loop of side $10 \ cm$ and resistance $0.5 \ \Omega$ is placed vertically in the east-west plane. $A$ uniform magnetic field of $0.10 \ T$ is set across the plane in the north-east direction. The magnetic field decreases to zero at $0.70 \ s$ at a steady rate. Then the magnitude of the induced current during this time interval will be . . . . . . .