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Asked in GSEB Board March 2022 · Snell's law, slabs and apparent depth
Given: three media, with the relative index written n_ij=(nᵢ)/(n_j).
Idea: write the wanted ratio in absolute indices and slip medium 1 in as a stepping stone.
n₃₂=(n₃)/(n₂)
Multiply and divide by n₁: (n₃)/(n₂)=(n₃)/(n₁)×(n₁)/(n₂)
The first factor is n₃₁ and the second is n₁₂.
So n₃₂=n₃₁× n₁₂ — medium 1 cancels, which is why light can be traced from 1 to 2 to 3 and the answer still depends only on 2 and 3.
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