Question

Find out the angle of refraction when a light travels from medium A to medium B.

Speed of light in A $=2\times {10}^{8}m/s$
Speed of light in B $=3\times {10}^{8}m/s$

• A. $si{n}^{-1}\left(\frac{4}{3}\right)$
• B. $si{n}^{-1}\left(\frac{1}{2}\right)$
• C. $si{n}^{-1}\left(\frac{3}{4}\right)$
• D. $si{n}^{-1}\left(\frac{1}{3}\right)$

Answer 1

The correct option is C

$si{n}^{-1}\left(\frac{3}{4}\right)$

According to Snell's law
${\mu }_{A}sini={\mu }_{B}sinr\Rightarrow \frac{sini}{sinr}=\frac{{\mu }_B}{{\mu }_A}\Rightarrow \frac{sin{30}^{\circ }}{sinr}=\frac{\frac{V_{air}}{V_B}}{\frac{V_{a}ir}{V_A}}=\frac{V_A}{V_B}=\frac{2\times {10}^8}{3\times {10}^8}=\frac{2}{3}\Rightarrow sinr=\frac{3}{2}\times sin{30}^{\circ }=\frac{3}{4}\Rightarrow r=si{n}^{-1}\left(\frac{3}{4}\right)$