AIPMT PRELIMS2007Physics-Optics
AIPMT PRELIMS 2007 Physics Refraction and Total Internal Reflection MCQ Question
Type: MCQ-conceptual-Medium-Class 12
A small coin is resting on the bottom of a beaker filled with liquid. A ray of light from the coin travels upto the surface of the liquid and moves along its surface. How fast is the light travelling in the liquid?
A
2.4 × 10⁸ m/s
B
3.0 × 10⁸ m/s
C
1.2 × 10⁸ m/s
D
1.8 × 10⁸ m/s
Correct Answer
Option C
Detailed Explanation
The speed of light in a medium is given by v = c/n, where c is the speed of light in vacuum and n is the refractive index. Since the light travels along the surface, it implies total internal reflection, and the critical angle condition gives the speed in the liquid.
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