Question

When the same monochromatic ray of light travels through glass slab and through water, the number of waves in glass slab of thickness 6cm is same as in water column of height 7cm. If refractive index of glass is 1.5, then refractive index of water is ______.

Options

• 1.258

• 1.269

• 1.286

• 1.310

Answer 1

When the same monochromatic ray of light travels through glass slab and through water, the number of waves in glass slab of thickness 6cm is same as in water column of height 7cm. If refractive index of glass is 1.5, then refractive index of water is 1.286.

Explanation:

∵ number of waves in glass slab = number of waves in water column 

∴ μ_g . h_g = μ_w . h_w

h_g = thickness of slab and h_w = height of water column.

or, μ_w = ${\displaystyle \frac{{\mu }_{\text{g}}.{\text{h}}_{\text{g}}}{\text{hw}}}$

= ${\displaystyle \frac{1.5\times 6}{7}}$ 

= 1.286