The magnitude of magnetic induction at a point in a magnetic field of area $25 {\mathrm{cm}}^2$ and magnetic flux $5\times {10}^{-4} \mathrm{Wb}$ is

In the figure shown, the magnet is pushed towards the fixed ring, along its axis and is made to pass through it.

Choose the correct option, based on the given information.

Consider the situation shown in the figure. If the current $i$ in the long straight wire $xy$ is increased at a steady rate the induced current in loop $A$ and $B$ will be

A black box $\left(BB\right)$ which may contain a combination of electrical circuit elements (resistor, capacitor or inductor) is connected with other external circuit elements as shown below in the figure $\left(a\right)$. After the switch $\left(S\right)$ is closed at time $t=0,$ the current $\left(I\right)$ as a function of time $\left(t\right)$ is shown in the figure $\left(b\right)$ From this we can infer that the black box contains