When white light passes through a prism, it splits into its constituent colours due to dispersion. The amount of bending (deviation) of light by a prism depends on the refractive index of the prism material for that specific colour. According to Cauchy's formula and experimental observations, the refractive index of a material decreases as the wavelength of light increases. Violet light has the shortest wavelength among the visible colours, while red light has the longest wavelength. Therefore, the refractive index of glass is highest for violet light and lowest for red light. A higher refractive index leads to a greater deviation (bending).
When a light beam falls on a triangular glass prism, a band of colours is obtained. Which one of the following statements is correct in this regard?
Asked in UPSC NDA 2 2021 · Topic: Optics (Prisms and Dispersion)
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Answer: C. Violet light bends the most, as the refractive index of glass for violet light is greatest.
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