Q1. [1] § 9.3.2 The Refractive Index
If the absolute refractive indices of two media X and Y are 6/5 and 4/3 respectively, then the refractive index of Y with respect to X will be :
- (A) 10/9
- (B) 9/10
- (C) 9/8
- (D) 8/9
Previously asked in CBSE board exam
2025 31/2/1 Q11
Generated by claude-sonnet-4-6 · 2026-06-15 06:48 · grounding rag
Model Answer
(A) 10/9
Using the relation: $n_{YX} = \dfrac{n_Y}{n_X} = \dfrac{4/3}{6/5} = \dfrac{4}{3} \times \dfrac{5}{6} = \dfrac{20}{18} = \dfrac{10}{9}$
Explanation
The refractive index of Y with respect to X equals the absolute refractive index of Y divided by the absolute refractive index of X (both measured with respect to air/vacuum). This follows from the relation $n_{21} = v_1/v_2$, where expressing both speeds relative to air gives $n_{YX} = n_Y / n_X$. Simply divide the two given values correctly.
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