Physics - Geometrical Optics Question with Solution | TestHub

Let the angle of incidence be $i$ and the angle of refraction be $r$.

Given $i=2r$.

According to Snell's law:

$\frac{\sin i}{\sin r}=\mu$

Substituting $i=2r$:

$\frac{\sin (2r)}{\sin r}=\mu$

$\frac{2\sin r\cos r}{\sin r}=\mu$

$2\cos r=\mu$

$\cos r=\frac{\mu }{2}$

$r={\cos }^{-1}\left(\frac{\mu }{2}\right)$

The angle of incidence is $i=2r$:

$i=2{\cos }^{-1}\left(\frac{\mu }{2}\right)$

Answer: $2{\cos }^{-1}\left(\frac{\mu }{2}\right)$