The charge which will flow through a galvanometer of resistance $200 \Omega$ connected to a $400 \Omega$ circular coil of $1000$ turns wound on a wooden stick $20 \ mm$ in diameter,if a magnetic field $B=0.012 \ T$ parallel to the axis of the stick is decreased suddenly to zero,is nearly: (in $\mu C$)

An insulated copper wire of $100$ turns is wrapped around a wooden cylindrical core of the cross-sectional area $24\,cm^2$. The two ends of the wire are connected to a resistor. The total resistance in the circuit is $12\,\Omega$. If an externally applied uniform magnetic field in the core along its axis changes from $1.5\,T$ in one direction to $1.5\,T$ in the opposite direction,the charge flowing through a point in the circuit during the change of magnetic field will be $.........\,mC$.

$A$ and $B$ are two metallic rings placed at opposite sides of an infinitely long straight conducting wire as shown. If current in the wire is slowly decreased,the direction of induced current will be

$A$ 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

The north pole of a bar magnet is moved swiftly downward towards a closed coil and then a second time it is raised upwards slowly. The magnitude and direction of the induced currents in the two cases will be of:

$A$ coil of effective area $3 \,m^2$ is placed at right angles to a magnetic field of induction $0.05 \,Wb/m^2$. If the field is decreased to $20 \%$ of its original value in $10 \,s$, the e.m.f. induced in the coil will be: (in $\,mV$)