$A$ coil has $200$ turns and an area of $70 \ cm^2$. The magnetic field perpendicular to the plane of the coil is $0.3 \ Wb/m^2$ and it takes $0.1 \ s$ to rotate through $180^o$. The value of the induced $e.m.f.$ will be ...... $V$.

$A$ uniform magnetic field $B$ that is perpendicular to the plane of the page passes through the loops,as shown. The field is confined to a region of radius $a$,where $a < b$,and is changing at a constant rate. The induced $emf$ in the wire loop of radius $b$ is $\varepsilon$. What is the induced $emf$ in the wire loop of radius $2b$?

The figure shows certain wire segments joined together to form a coplanar loop. The loop is placed in a perpendicular magnetic field in the direction going into the plane of the figure. The magnitude of the field increases with time. $I_1$ and $I_2$ are the currents in the segments $ab$ and $cd$. Then,

In the given figure,the magnet is moved towards the coil with speed $v$ and the induced $emf$ is $e$. If the magnet and the coil recede away from one another,each moving with speed $v$,the induced $emf$ in the coil will be

The following figure shows planar loops of different shapes moving into or out of a region of a magnetic field which is directed normal to the plane of the loop,away from the reader. Determine the direction of the induced current in each loop using Lenz's law.

$A$ coil having $n$ turns and resistance $R \ \Omega$ is connected with a galvanometer of resistance $4 R \ \Omega$. This combination is moved in time $t$ seconds from a magnetic flux $\phi_1$ Weber to $\phi_2$ Weber. The induced current in the circuit is