CBSE Class 12 · 2017 · Geometrical OpticsVery Short Answer

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When light travels from a rarer medium to a denser medium, the speed of light decreases. Does the reduction in speed imply a reduction in the energy carried by the light?

Answer: No.

Solution

The energy of a light wave depends on its \emph{frequency} (and amplitude), not on its speed. On refraction the frequency stays unchanged; only the speed and wavelength change. Hence the reduction in speed does \emph{not} mean a reduction in energy.

CBSE Class 12 Board · 2017 · Subjective

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