Question

In a thin prism of glass (refractive index $1.5$), which of the following relations between the angle of minimum deviation ${\delta }_m$ and angle of refraction $r$ will be correct?

• A. ${\delta }_m=r$
• B. ${\delta }_m=1.5r$
• C. ${\delta }_m=2r$
• D. ${\delta }_m=\frac{r}{2}$

Answer 1

The correct option is A ${\delta }_m=r$

For a thin prism $\delta =(\mu -1)A$

Also at angle of minimum deviation, $r=A/2$

So, ${\delta }_{min}=(\mu -1)2r$

=> ${\delta }_{min}=(1.5-1)2r$

=> ${\delta }_{min}=r$