Question

A wave has velocity $v$ in medium $P$ and velocity $2v$ in medium $Q$. If the wave is incident in medium $P$ at an angle of $30^{\circ}$, then the angle of refraction will be

• A. $30^{\circ}$
• B. $45^{\circ}$
• C. $60^{\circ}$
• D. $90^{\circ}$

Answer 1

Answer: (D)

$90^{\circ}$

Answer 2

$v =\frac{\sin i }{\sin r }=\frac{ v _{1}}{ v _{2}}$
$\Rightarrow \sin r =\sin 30^{\circ} \times \frac{2 v }{ v }$
$\Rightarrow \sin r =\frac{1}{2} \times 2 \times 1$
$\Rightarrow r =90^{\circ}$