"The polarity of induced emf is such that it tends to produce a current which opposes the change in magnetic flux that produced it." This statement is known as . . . . . . law.

As shown in the figure, two identical conducting rings of radius $r$ are placed in a magnetic field. In figure $(a)$, the magnetic field is increasing at the rate of $0.3 \text{ T/s}$, and in figure $(b)$, the magnetic field is decreasing at the rate of $0.2 \text{ T/s}$. The direction of the current in ring $(a)$ and ring $(b)$, when observed from the top, is . . . . . .

The magnetic field $B$ crossing normally a square metallic plate of area $4\,m^2$ changes with time as shown in the figure. The magnitude of the induced $emf$ in the plate during $t=2\,s$ to $t=4\,s$ is $..........\,mV$.

The north pole of a long horizontal bar magnet is being brought towards a closed circuit consisting of a coil. The direction of the induced current produced in it is

The magnetic flux through a coil of resistance $10\,\Omega$ is changed by $\Delta \phi$ in $0.1\,s$. The resulting current in the coil varies with time as shown in the figure. Then,the magnitude $\left| \Delta \phi \right|$ is equal to (in weber):

$A$ closed planar wire loop of area $A$ and arbitrary shape is placed in a uniform magnetic field of magnitude $B$,with its plane perpendicular to the magnetic field. The resistance of the wire loop is $R$. The loop is now turned upside down by $180^o$ so that its plane again becomes perpendicular to the magnetic field. The total charge that must have flowed through the wire ring in the process is