Question

a light ray moves from air to denser medium angle of incindence 45 if angle of refraction is 30 then find out time taken by light ray and covering 10km distance in denser medium

Answer 1

refractive index for 2nd medium = sin i ÷ sin r
= sin45 ÷ sin30 = √2 = 1.414
as we know , refractive index is also = c÷v

then 1.414 = c÷v (value for speed of light (c)= 3× 10^8 m/sec
then v will be find out by solving the eqn.
after that you have find out the speed then you can find out time taken to travel 10 km.