A thin prism P_1 with angle 4^@ 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. What is the angle of the prism P_2?

A thin prism P_1 with angle 4^@ and made from glass of refractive inde

1.	A thin prism P_1 with angle 4^@ 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. What is the angle of the prism P_2?
Answer» Solution :In CASE of thin prism `DELTA=(mu-1)A` when two prism are combined together `delta=delta_1+delta_2=(mu-1) A +(mu-1)A.` For producing DISPERSION without deviation `delta=0 i.e., (mu-1)A.=-(mu-1) A ` or `A.=- ((1.54-1))/((1.72-1)) times 4^@=-3^@` So the ANGLE of the other prism is `3^@` and opposite to the first.