Question

A beam of light consisting of red, green and blue colors is incident on a right angled prism. The refractive index 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 1

Answer:

Explanation:

The beam of light is incident on the face AB of the right angled prism ABC. Thus no refraction occurs at the face of AB and passes straight and strikes the face AC at an angle of incidence, 45° For total reflection to take place at face AC,

= i>ic or sini> sin ic where,

Critical angle -

sin c = Refractive index of rarer medium / Refractive index of denser medium

where, when the angle of incidence travels from a dense medium to rarer medium it is greater than critical angle and no refraction occurs.

Angle of incidence i at surface AC= 45°

Thus, critical Angle of incidence  -

sin c = 1/c

For red ur =1.39

For green ug =1.44

For blue ub =1.47

Since refractive index of green and blue is greater than √2 and their critical angles are less than 45°, so green and blue will be completely reflected whereas red will emerge out of prism. Hence red will be separated from the light green and blue.