OPSC OAS 2020 PrelimsScience & TechnologyQuestion 16
Solved previous year question from the OPSC OAS/OCS 2020 Preliminary Examination (General Studies), with the official answer key and a detailed explanation.
Question
Which one of the following colours is least deviated by the glass prism?
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Answer & Explanation
Correct answer: (B) Red
- Red light is the least deviated (bent) when passing through a glass prism. This is because red light has the longest wavelength and lowest frequency among all visible light colours, and the degree of deviation is inversely proportional to wavelength — longer the wavelength, lesser the deviation.
Dispersion of White Light through a Prism
- When white light passes through a glass prism, it splits into seven constituent colours known as VIBGYOR (Violet, Indigo, Blue, Green, Yellow, Orange, Red).
- This phenomenon is called dispersion of light. Each colour bends by a different amount because each has a different wavelength and refractive index in glass.
