Rankers Physics

Refraction by Prism: Practice Problem & Solution

A ray of light is incident at an angle of incidence, i, on one face of prism of angle A (assumed to be small) and emerges normally from the opposite face. If the refractive index of the prism is $\mu$, the angle of incidence i, is nearly equal to: (2012 Pre)
$\mu A$
$\frac{2\mu}{A}$
$\frac{A}{\mu}$
$\frac{A}{2\mu}$

Solution Explained:

To solve this problem, we apply the core principles of Refraction by Prism. Understanding the underlying formula is key to arriving at the correct answer below:

Since the ray emerges normally, $r_2 = 0$, which means $r_1 = A$. For small angles, Snell's law gives $i = \mu r_1$. Substituting $r_1 = A$, the angle of incidence is $i = \mu A$.

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