Question

Time taken by the sun light pass through window ofthickness 4 mm whose refractive index 1.5

Answer 1

refractive index of glass = 1.5  of window
speed of light inside glass window = 3 * 10⁸ m/s / 1.5
         = 2 * 10⁸ m/s

Time taken to travel 4mm =   0.004 /2*10⁸  = 0.02 nano sec