Question

A glass slab of thickness 4 cm contains the same number of waves as in 'x' cm of water column when both are traversed by the same monochromatic light. If the refractive indices of glass and water for that light are `5/3` and `4/3` respectively, the value of x will be ______.

Options

• `9/20  `cm

• `20/9  `cm

• 5 cm

• `5/4  `cm

Answer 1

A glass slab of thickness 4 cm contains the same number of waves as in 'x' cm of water column when both are traversed by the same monochromatic light. If the refractive indices of glass and water for that light are `5/3` and `4/3` respectively, the value of x will be 5 cm.

Explanation:

`"n"_g/"n"_omega=5/3xx3/4=5/4`

`lambda_g/lambda_omega="n"_g/"n"_omega=5/4`

since the number of wares is same we have

`X/4=5/4`

∴ x = 5 cm