Question

A crown glass prism is combined with flintone to produce a hybrid optical appratus in such a way that the mean by passes undeviated. If crown prism is of angle 5?, then angle of the flint glass prism will be (for crown and flint glasses the refractive indices are 1.517 and 1.620, respectively).

• A. 5?
• B. 4?
• C. 7?
• D. 9?

Answer 1

Answer: (B)

The deviation produced by crown prism is $\delta =(\mu -1)A$ and that by flint glass is ${\delta }^{\prime }=({\mu }^{\prime }-1)A^{\prime }$ In case of no net deviation $\delta ={\delta }^{\prime }$ $A^{\prime }=\left[\frac{(\mu -1)}{({\mu }^{\prime }-1)}\right]A=\frac{1.517-1}{1.620-1}\times 5^o$ $=4.2\simeq 4^o$