Can you explain internal refraction in prism?

What is the relationship between critical angle and refractive index?

Asked by sscv2005 | 10th Apr, 2020, 10:15: AM

Expert Answer:

Total internal reflection: It is the phenomenon when a ray of light travelling in a denser medium, is incident at the surface of a rarer medium such that the angle of incidence is greater than the critical angle for the pair of media, the ray is totally reflected back into the denser medium. 
When total internal reflection occurs from a prism, the entire incident light (100%) is reflected back into the denser medium.


As shown in diagram, a beam of light is incident on face AB of the prism normally so it passes undeviated and strikes the face AC where it makes an angle of 45° with the normal to AC. Because here the incident angle is more than critical angle so rays suffer total internal reflection and reflect at angle of 45°. The beam then strikes face BC, where it is incident normally and so passes undeviated. As a result the incident beam gets deviated through 90°.

Relation between refractice index and critical angle:-

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Answered by Shiwani Sawant | 10th Apr, 2020, 12:50: PM