An inductor coil wound uniformly has self inductance 'L' and resistance 'R'. The coil is broken into two identical parts. The two parts are then connected in parallel across a battery of 'E' volt of negligible internal resistance. The current through battery at steady state is

Two wires of same material of radius 'r' and '2r' respectively are welded together end to end. The combination is then used as a sonometer wire under tension 'T'. The joint is kept midway between the two bridges. The ratio of the number of loops formed in the wires such that the joint is a node is

A ray of light travels from a denser medium to a rarer medium. The reflected and the refracted rays are perpendicular to each other. If '$$r$$' and '$$r_1$$' are the angle of reflection and refraction respectively and '$$\mathrm{C}$$' is the critical angle, then the angle of incidence is

Specific heats of an ideal gas at constant pressure and volume are denoted by $$\mathrm{C}_{\mathrm{p}}$$ and $$\mathrm{C}_{\mathrm{v}}$$ respectively. If $$\gamma=\frac{\mathrm{C}_{\mathrm{p}}}{\mathrm{C}_{\mathrm{v}}}$$ and $$\mathrm{R}$$ it's the universal gas constant then $$\mathrm{C}_{\mathrm{v}}$$ is equal to