Question

Direction: In the question Assertion (A) and Reason (R) are given then the correct answers will be as:
(A) Refractive index of prism depends only on the kind of glass of which it is made of and the colour of light
(R) The refractive index of prism depends upon he refracting angle of the prism and the angle of minimum deviation:

• A. If both (A) and (R) are true and (R) is the correct explanation of the (A)
• B. If both (A) and (R) are true but (R) is not the explanation of (A)
• C. If (A) is true but (R) is false
• D. If (A) is false but (R) is true

Answer 1

Answer: (C)

As the refractive index of a prism depends upon the material of prism and the colour of light
i.e., it is maximum for violet rays and minimum for red rays.
But the refractive index depends upon the angle of prism and angle of minimum deviation $\delta_{m}$ and is given by a $\mu=\frac{\sin \frac{A+\delta_{m}}{2}}{\sin \frac{A}{2}}$ but not on the refracting angle of the prism.
Hence assertion is true but reason is wrong.