For a light ray to undergo total internal reflection ( $\mathrm{i}=$ angle of incidence, $\mathrm{i}_{\mathrm{c}}=$ critical angle)

With gradual increase in frequency of an a.c. supply, the impedance of an LCR series circuit

Two parallel plate air capacitors of same capacity ' C ' are connected in series to a battery of emf ' $E$ '. Then one of the capacitors is completely filled with dielectric material of constant ' K '. The change in the effective capacity of the series combination is

Assuming that the earth is revolving around the sun in circular orbit of radius R , the angular momentum is directly proportional to $\mathrm{R}^{\mathrm{n}}$. The value of ' $n$ ' is