The critical angle for light ray going from medium-1 to medium-2 is $i_{c}$. What will be the speed of light in medium-2, if its value in medium-1 is u?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → $\frac{u}{\sin i_c}$
The refractive index (u) of a medium is related to the speed of light in the medium (v) by -
$u=\frac{c}{v}$
$∴u_1=\frac{c}{v_1}$ [Medium 1]
$u_2=\frac{c}{v_2}$ [Medium 2]
and,
$\sin i_c=\frac{u_2}{u_1}$ [$i_c$ = critical angle]
$\sin i_c=\frac{\frac{c}{v_2}}{\frac{c}{v_1}}=\frac{u}{v_2}$ [$v_1=u$]
$v_2=\frac{u}{\sin i_c}$$