Light travels through a glass plate of thickness t and refractive index `mu.` If c is the speed of light in vacuum, the time taken by light to travel this thickness of glass is

Options

A. `t mu c`
B. `(tc)/(mu)`
C. `(t)/(muc)`
D. `(mu t)/(c)`

Answer

D

Explanation

Time taken by light ray to pass through glass slab = `(mu t)/(c)`
where t = geometrical path
`mut` = optical path