The armature of a DC motor has $20 \mathrm{\Omega }$ resistance. It draws a current of $1.5 \mathrm{A}$ when run by the $220 \mathrm{V}$ DC supply. The value of back emf induced in it will be 

As shown in the figure, a magnet is moved with a fast speed towards a coil at rest. Due to this induced e.m.f., induced current and induced charge in the coil is $E, I$ and $Q$ respectively. If the speed of the magnet is doubled, the incorrect statement is

A magnet $N-S$ is suspended from a spring and when it oscillates, the magnet moves in and out of the coil $C$. The coil is connected to galvanometer $G$. Then, as the magnet oscillates, $G$ shows

As shown in figure, $A$ and $B$ are two coaxial conducting loops separated by some distance. When the switch $S$ is closed, a clockwise current $/$flows in $A$ (as seen by $O$ ) and an induced current $I_1$ flows in $B$. The switch remains closed for a long time. When $S$ is opened, a current $I_2$ flows in $B$. Then the directions of $I_1$and $I_2$ (as seen by $O$) are

There are two loops $A$ and $B$ placed coaxially along vertical line. Loop $A$ is allowed to fall freely towards loop $B$. If constant current flowing in loop $A$ is as shown in the figure, then find the direction of flow of induced current in loop $B$ as seen from the bottom of loop $B$