CBSE Class 12-science Answered

^aμ_b = Refractive index of b w r t a = speed of light in a/speed of light in b

^aμ_{g =} Refractive index of glass w r t air = speed of light in air/speed of light in glass

^aμ_{w =} Refractive index of water w r t air = speed of light in air/speed of light in water = 4/3

^aμ_g/^aμ_w = speed of light in water/speed of light in glass = wavelength in water/wavelength in glass

{ since speed = wavelengthxfrequency and frequency will be the same water and glass as it doesn't change due to energy conservation }

wavelength in water = thickness of water layer/number of waves

wavelength in glass = thickness of glass/number of waves.

since the number of waves is same both the media,

wavelength in water/wavelength in glass = water thickness/glass thickness = 5/4.

^aμ_g/^aμ_w = 5/4

^aμ_g = 5^aμ_w/4

^aμ_g = 5/3

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Team,

TopperLearning.