Question

A thin prism is made of a material having refractive indices 1.61 and 1.65 for red and violet light. The dispersive power of the material is 0.07. It is found that a beam of yellow light passing through the prism suffers a minimum deviation of `4.0^@` in favourable conditions. Calculate the angle of the prism.

Answer 1

Given that : `mu_r=1.61`
`mu_v=1.65`
`omega=0.07 and delta_y=4^@`
Now `w=(mu_v-mu_r)/(mu_y-1)`
`=0.07=(1.65-1.61)/(mu_y-1)`
`mu_y-1=0.04/0.07=4/7`
Again `delta=(mu-1)A`
`rarr A=delta_y/(mu_y-1)=4/(4/7) =7`