AIPMT PRELIMS2001Physics-Optics
AIPMT PRELIMS 2001 Physics Total Internal Reflection MCQ Question
Type: MCQ-conceptual-Hard-Class 12
A disc is placed on a surface of pond which has refractive index 5/3. Å source of light is placed 4 m below the surface of liquid. The minimum radius of disc will be so light is not coming out
A
∞
B
2m
C
3m
D
4m
Correct Answer
Option B
Detailed Explanation
For total internal reflection, the light must not escape. The critical angle is such that sin(θc) = 1/n. Here, n = 5/3, so θc = sin⁻¹(3/5). The light will not escape if the radius is infinite.
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