Question

A vertical pencil of rays comes from bottom of a tank filled with a liquid. When it is accelerated with an acceleration of 7.5 m/s${}^2$, the ray is seen to be totally reflected by liquid surface. What is minimum possible refractive index of liquid?

• A. slightly greater than 4/3
• B. slightly greater than 5/3
• C. slightly greater than 1.75
• D. slightly greater than 1.5

Answer 1

Answer: (B)

$tan\theta =a/g={37}^o\Rightarrow {\theta }_c<{37}^o$

$sin{\theta }_c=sin37\Rightarrow \mu >5/3$