Question

Refraction of light from air to glass and from air to water are shown in figure (i) and figure (ii) below. The value of the angle $\theta$ in the case of refraction as shown in figure (iii) will be

• A. $30^{\circ}$
• B. $35^{\circ}$
• C. $60^{\circ}$
• D. $41^{\circ}$

Answer 1

Answer: (B)

Using Snells law,
$\,{}^{a}\mu_{g} = \frac{sin \,60^{\circ}}{sin\, 35^{\circ}}, \,{}^{a}\mu_{w} =\frac{ sin \,60^{\circ}}{sin \,41^{\circ}} $
and $\,{}^{w}\mu_{g} = \frac{sin\, 41^{\circ}}{sin\, \theta} $
$\,{}^{a}\mu_{w} \times ^{w}\mu_{g} = \,{}^{a}\mu_{g} $
$\Rightarrow \frac{sin\, 60^{\circ}}{sin\, 41^{\circ}} \times\frac{sin \,41^{\circ}}{sin\, \theta} = \frac{sin \,60^{\circ}}{sin \,35^{\circ}} $
$\Rightarrow sin \,\theta = sin \,35^{\circ} $ or
$ \theta = 35^{\circ}$