A beam of light consisting of red, green and blue colours is incident on a right angled prism, fig. The refractive indices of the material of the prism for the above red, green and blue wavelengths are 1.39, 1.44 and 1.47 respectively. The prism will `

Answer

Red rays will be transmitted.

Explanation

As `ABC` is an isoceles right angled prism, angle of incidence of each ray is `45^@`. If crictical angle `C` is less than `45^@`, the ray will be totally internally reflected at `AC`. When `/_C gt 45^@`, the ray will be transmitted through the face `AC`
For red ray, `mu = 1.39`
`sin C = (1)/(mu) = (1)/(1.39) = 0.719, C = 46.0^@`
`:.` Red ray will be transmitted.
For green ray, `mu = 1.424`,
`sin C = (1)/(mu) = (1)/(1.424) = 0.702, C = 44.6^@`
`:.` green ray will also be reflected at face `AC`
For blue ray, `mu = 1.476`,
`sin C = (1)/(mu) = (1)/(1.476) = 0.678, C = 42.6^@`
`:.` Blue ray will also be reflected at face `AC`.