Question

A light ray travels from denser to rarer. Plot between $\delta$ (deviation) vs i (incidence angle) is shown in figure, then which is the correct relation between Y & X?

• A. $Y=X$
• B. $Y=3X$
• C. $Y=\frac{X}{3}$
• D. $Y=2X$

Answer 1

The correct option is D $Y=2X$

For refraction $\delta =|r-i|$ and for reflection $\delta =180-2i$

First part of graph is for refraction $\delta =r-i$
$\delta =90-{\theta }_C$

For start of second graph,
$\delta =180-2i=180-2{\theta }_C$
$Y=180-2{\theta }_C$
$X=90-{\theta }_C$
$\frac{Y}{X}=2$
$Y=2X$