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Consider three media P, Q and R with refractive indices 1, 1.25, and 1.5, respectively. The medium Q having a thickness of 5 cm is placed between extended media P and R as shown in the figure. An object O is placed at the centre of medium Q. If viewed from medium P near the normal direction, the apparent depth of O is h₁. For similar observation from medium R, the apparent depth is h₂. The value of |h₁-h₂|, in cm, is :

Asked in Re-NEET 2026 · Snell's law, slabs and apparent depth

Figure: Snell's law, slabs and apparent depth
Answer: (2) 1

Step-by-step solution

O is 2.5 cm from each face of Q.

Seen from P: h₁=2.5×(μ_P)/(μ_Q)=2.5×1/(1.25)=2 cm.

Seen from R: h₂=2.5×(μ_R)/(μ_Q)=2.5×(1.5)/(1.25)=3 cm.

|h₁-h₂|=1 cm.

Why the other options are wrong

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