A prism is made of glass of unknown refractive index. A parallel beam of light is incident on a face of the prism. The angle of minimum deviation is measured to be 40o. What is the refractive index of the material of the prism? The refracting angle of the prism is 60o. If the prism is placed in water (refractive index 1.33), predict the new angle of minimum deviation of a parallel beam of light.
The angle of the prism, 60o.Minimum deviation
δ=40oμ′ is the refractive index of the material of the prism.
μ′=sin(A+δm2)sin(A2)=1.5321
Let δ1 be new minimum deviation, now it is put under water μ=1.33
⇒μ′μ=sin(A+δm2)sin(A2)
⇒δ1=10.32o