A ray of light strikes a glass slab (from air). Which one of the follo

A ray of light strikes a glass slab (from air). Which one of the following is NOT correct?

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The speed of light in glass is less than that in air

The frequency of light in glass is same as that in air

The wavelength of light in glass is less than that in air

The frequency of light in glass is less than that in air

Answer is Right!

Answer is Wrong!

This question was previously asked in

UPSC Geoscientist – 2021

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When light passes from one medium (air) to another medium (glass), its speed decreases, and its wavelength decreases. However, the frequency of the light wave is determined by the source and remains constant as it passes from one medium to another. Therefore, the statement “The frequency of light in glass is less than that in air” is incorrect.

The speed of light (v), frequency (f), and wavelength (λ) are related by the equation v = fλ. When light enters a denser medium like glass from air, its speed (v) decreases, and since the frequency (f) remains constant, the wavelength (λ) must decrease proportionally (λ = v/f).

The change in speed and wavelength causes the bending of light, known as refraction. The refractive index of a medium is defined as the ratio of the speed of light in vacuum to the speed of light in the medium.

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