Question

A thin prism $P_1$ with angle $4^{\circ }$ and made from glass of refractive index 1.54 is combined with another prism $P_2$ made from glass of refractive index 1.72 to produce dispersion without deviation. the angle of prism $P_2$ is :

• A. ${5.33}^{\circ }$
• B. $4^{\circ }$
• C. $3^{\circ }$
• D. ${2.6}^{\circ }$

Answer 1

The correct option is C $3^{\circ }$

For dispersion without deviation,

$({\mu }_1-1)\times A_1=({\mu }_2-1)\times A_2$

${\mu }_1=1.54,A_1=4°,{\mu }_2=1.72$

$(1.54-1)\times 4=(1.72-1)\times A_2$

=> $A_2=3^{\circ }$.