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The refractive index of a glass is 1.520 for red light and 1.525 for blue light. Let D1 and D2 be the angles of minimum deviation for red and blue respectively in a prism of this glass. Then,

1. D1 < D2
2. D1 = D2
3. D1 can be less than or greater than D2 depending upon the angle of prism
4. D1 > D2

Correct answer: D1 < D2

Solution

The refractive index of a material determines how much light bends when passing through it; since red light has a lower refractive index than blue light, it will experience less deviation in the prism, resulting in a smaller angle of minimum deviation for red light compared to blue light.

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