Two transparent media A and B are adjacent to each other. Velocity of light in medium A is `2 xx 10^(8)m * s^(-1)` and in medium B it is `2.5 xx 10^(8)m*s^(-1)`. If ray of light under goes total internal reflection when travelling from A to B then what is the critical angle for the pair of media?

Answer

`sin-1(4)/(5)`