Question

A crown glass prism of angle ${6.20}^0$ is to be combined with a flint glass prism in such a way that the mean ray passes undeviated. The angle of the flint glass prism needed if the refractive indices of crown glass and flint glass for yellow light are 1.517 and 1.620 respectively is

• A. 2.6${}^{\circ }$
• B. 5.17${}^{\circ }$
• C. 51.7${}^{\circ }$
• D. 26${}^{\circ }$

Answer 1

Answer: (B)

5.17${}^{\circ }$

For the ray to pass undeviated, the deviation produced by the 2 prisms should be equal
$({\mu }_1-1)A_1=({\mu }_2-1)A_2$
Substituting the respective values, we get,
$A_2=5.17$