A compass needle which is allowed to move in a horizontal plane is taken to a geomagnetic pole. It

A coil of resistance 400 $$\Omega $$ is placed in a magnetic field. If the magnetic flux $$\phi $$ (Wb) linked with the coil varies with time t (sec) as $$\phi = 50{t^2} + 4$$.

The current in the coil at t = 2 sec is

The current $$(I)$$ in the inductance is varying with time according to the plot shown in figure.


Which one of the following is the correct variation of voltage with time in the coil ?

In an electrical circuit R, L, C and a.c. voltage source are all connected in series. When L is removed from the circuit, the phase difference between the voltage and the current in the circuit is If instead, C is removed from the circuit, the phase difference is again. The power factor of the circuit is