It takes nd/ (lambda*f) time or a short pulse of light to travel from one end of the glass to the other.
If we talk about free space, that is, vacuum, light travels at a speed of 3x10^8 m/s, yet inside a glass light travels at a speed of v= c/n, where v is the velocity of the light and n is the refractive index. Now,
v=d/t,
so t= d/v
t= d/ (c/n)= n*d/c
c= lambda*f
t= nd/(lambda*f)
here, d is the thickness of the block, t is the time required and c refers to speed of light.
To learn more about refractive index, click
brainly.com/question/13088981
#SPJ4
