Question

19. When light goes from air to a medium, its speed
decreases by 30%. The refractive index of this
medium w.r.t. water is (uw = 4/3).
​

Answer 1

Answer:

the speed of medium speed decreases by 30 percentage the refractive index of=4/3(=n=c/v)

Answer 2

Answer:

The answer will be 1.42

Explanation:

According to the problem the speed of light is decreased

Now we know that the speed of light is c

As it is decreased by 30%

Therefore the speed of light  on that medium will be=  c - c x 0.3= 0.7 c

Now we know that the refractive index of any medium = speed of light in air /speed of light in the particular medium = c/0.7c = 10/7 = 1.42