Question

Which is a greater angle of incidence or angle of refraction ,when light travels from denser medium to rarer medium.

Answer 1

$1.$When a ray of light travels from an optically denser medium to an optically rarer medium, it always bends away from the normal.
$2.$ According to the Snell's law
${\mu }_1\times \sin {\theta }_1={\mu }_2\times \sin {\theta }_2$
Where ${\theta }_1=angleofincidence$, ${\theta }_2=angleofrefraction$
$3.$For an optically denser medium, refractive index ${\mu }_1$​ is greater than that of the rarer medium ${\mu }_2$.
As ${\mu }_1>{\mu }_2$,

From the Snell's law,

$$\begin{gathered} \frac{\sin {\theta }_2}{\sin {\theta }_1}=\frac{{\mu }_1}{{\mu }_2} \\ \frac{\sin {\theta }_2}{\sin {\theta }_1}>1 \\ \sin {\theta }_2>\sin {\theta }_1 \end{gathered}$$

Therefore ${\theta }_1<{\theta }_2$
Thus, the angle of refraction has to be greater than the angle of incidence i.e. it bends away from the normal.