For refraction through a prism at minimum deviation, consider the statements: (A) the refracted ray inside the prism becomes parallel to the base; (B) a larger prism angle necessarily gives a smaller minimum deviation; (C) angle of incidence equals angle of emergence; (D) except at the minimum-deviation setting, there are generally two incidence angles giving the same deviation; (E) the angle of refraction becomes double the prism angle. Choose the correct set.
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Question

For refraction through a prism at minimum deviation, consider the statements: (A) the refracted ray inside the prism becomes parallel to the base; (B) a larger prism angle necessarily gives a smaller minimum deviation; (C) angle of incidence equals angle of emergence; (D) except at the minimum-deviation setting, there are generally two incidence angles giving the same deviation; (E) the angle of refraction becomes double the prism angle. Choose the correct set.

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G1 Physics · Accepted Answer

At minimum deviation, the ray path through a prism is symmetric. Therefore, i = e and r₁ = r₂ = A/2. So statement C is true. For the usual symmetric minimum-deviation ray in a prism, the internal ray is parallel to the base, so A is true. The deviation-versus-incidence curve has two incidence angles for the same deviation on the two sides of the minimum, except exactly at minimum deviation. Hence D is true. B is false: increasing prism angle does not necessarily reduce minimum deviation. E is f…