$A$ 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 ........... $V.$

Which scientist showed that by changing magnetic field an electric field can be obtained?

$A$ 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 field $W_1$ weber to $W_2$ weber. The induced current in the circuit is

$A$ conducting circular coil is placed in a uniform magnetic field with the magnetic field initially directed perpendicular to the plane of the coil. In step $A$,the coil is rotated from its initial position by $60^{\circ}$ about its diameter in time $t$. In step $B$,the coil is further rotated about the same axis in the same sense by another $120^{\circ}$ in time $2t$. The ratio of the emf induced in the coil in step $A$ to that in step $B$ is:

$A$ 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 $V$)

$A$ conducting ring is placed around the core of an electromagnet as shown in the figure. When key $K$ is pressed,the ring