Q. If sound travelling at $340\ ms\ \bar{}¹$ enters water where its speed becomes $1480\ ms\ \bar{}¹,$ then critical angle for total internal reflection is
A) $13.3{^\circ}$
B) $89.7{^\circ}$
C) $86.7{^\circ}$
D) $10.3{^\circ}$
Explanation
(a) We have
$\sin{C = \frac{1}{\mu}}$
$But\ \mu = \frac{v_{2}}{v_{1}} = \frac{1480}{340}$
$\therefore\sin{C = \frac{340}{1480}}$
$Or\ C = \sin^{- 1}\left( \frac{340}{1480} \right)$
$\ \ \ \ \ \ \ \ \ \ = 13.28{^\circ} \approx 13.3{^\circ}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.