The critical angle is for a light going from medium P to medium Q. If speed of light in medium P is V _ P then speed of light in medium Q is

Step-by-step solution

For total internal reflection for critical incidence angle the angle of refraction is 2 . Using Snell's law: n _ A = n _ B ( 2 ) , where, n _ A = refractive index of medium A and n_B= refractive index of medium B and n _ B = refractive index of medium B n_A n_B = 1 We define refractive index in terms of velocity of light as follows: aligned & n _ A n _ B = . V _ B (velocity in medium B ) . V _ A (velocity in medium A ) & V _ A V _ B = 1 & V _ B = V _ A = V aligned