Question

A ray of light, travelling in a medium of refractive index $\mu$, is incident at an angle $i$ on a composite transparent plate consisting of three plates of refractive indices ${\mu }_1,{\mu }_2$ and ${\mu }_3$. The ray emerges from the composite plate into a medium of refractive index ${\mu }^{,}$, at angle $x$, Then

• A. $sinx=sini$
• B. $sinx=\frac{\mu }{{\mu }^{,}}sini$
• C. $sinx=\frac{{\mu }^{,}}{\mu }sini$
• D. $sinx=\frac{{\mu }_1}{{\mu }_2}.\frac{{\mu }_3}{{\mu }_2}sini$

Answer 1

The correct option is B $sinx=\frac{\mu }{{\mu }^{,}}sini$

Applying Snell's law at point of incidence and point of emergence, we have

$\mu sini={\mu }^{\prime }sinx$

$sinx=\frac{\mu }{{\mu }^{\prime }}sini$