Refraction by Plane Surfaces: Practice Problem & Solution
An air bubble in a glass slab with refractive index $1.5$ (near normal incidence) is $5 cm$ deep when viewed from one surface and $3 cm$ deep when viewed from the opposite surface. The thickness (in cm) of the slab is: (2016 - II)
Solution Explained:
To solve this problem, we apply the core principles of Refraction by Plane Surfaces. Understanding the underlying formula is key to arriving at the correct answer below:
Total apparent depth of the air bubble is the sum of apparent depths from both sides: $d_{app} = 5 + 3 = 8 cm$.
Apparent depth is related to real thickness T by $d_{app} = \frac{T}{\mu}$.
Therefore, real thickness $T = d_{app} \times \mu = 8 \times 1.5 = 12 cm$.
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