Question

A thin prism $P_1$ with angle $4^o$ and made of glass of refractive index $1.54$ is combined with another prism $P_2$ made of glass of refractive index $1.72$ to produce dispersion without deviation. The angle of the 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 $3^{\circ }$

Dispersion without deviation is given by the relation,

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

$\Rightarrow (1.54-1)\times 4^0=(1.72-1)\times A_2$

=>$A_2=3^0$ Hence correct answer is C.