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A ring angled isosceles prism KLM of refractive index n_(1) is placed inside a rectangular block PQRS of refractive index n_(2) as shown in the adjoining Fig. The rectangular box is surrounded by a medium of refractive index n_(3). A ray of light AB enters the rectangular block normally. Depending upon the relationships between n_(1), n_(2) and n_(3). it takes one of the four possible paths. Under what condition the ray follows the path no. 2 (i.e., path ABCIJ)? |
| Answer» Solution :The RAY no. 2 bends away from normal while undergoing REFRACTION at C and bends further away from the normal while undergoing refraction at I. It means that `n_(3) lt n_(2) lt n_(1)`. However, the light ray does not suffer total internal reflaction at C, hence it is CLEAR that `n_(2) gt (n_(1))/(SQRT2).` Hence we CONCLUDE that `n_(1) gt n_(2) gt (n)/(sqrt2) and n_(3) lt n_(2)`. | |