Question

State one factor on which a critical angle for a given pair of media depends. The critical angle for the glass-air interface is 45° for the yellow light. Will it be equal to, less than or greater than 45° for (i) red light, (ii) blue light?

Answer 1

The value of the critical angle for a given pair of media depends on the colour of light.
(Hint: Remember VIBGYOUR Violet has minimum i_c whereas Red has maximum).
(i) For red light, the critical angle will be greater than 45°.
(ii) For blue light, the critical angle will be less than 45 °.