The magnetic potential energy stored in a certain inductor is 25 mJ, when the current in the inductor is 60 mA. This inductor is of inductance

Current sensitivity of a moving coil galvanometer is 5 div/mA and its voltage sensitivity (angular deflection per unit voltage applied) is 20 div/V. The resistance of the galvanometer is

An inductor 20 mH, a capacitor 100 $$\mu $$F and a resistor 50 $$\Omega $$ are connected in series across a source of emf, V = 10 sin 314 t. The power loss in the circuit is

The refractive index of the material of a prism is $$\sqrt 2 $$ and the angle of the prism is 30°. One of the two refracting surfaces of the prism is made a mirror inwards, by silver coating. A beam of monochromatic light entering the prism from the other face will retrace its path (after reflection from the silvered surface) if its angle of incidence on the prism is