InterviewSolution
Saved Bookmarks
InterviewSolution
| 1. |
A rectangle glass wedge (prism) is immersed in water as shown in figure E-a. For what value of angle alpha, will the beam of light, which is normally incident on AB, reach AC entirely as shown in figure E-b. Take the refractive index of water as 4/3 and the refractive index of glass as 3/2. |
Answer» Solution :From the geometry of figure E-b it is clear that, the angle of incidence on the side BC is equal to `ALPHA` (dotted line is a normal drawn at the point of incidence). The ray should undergo total internal reflection to reach AC. For occurrence of total internal reflection, the value of `alpha` must be greater than the CRITICAL angle at interface of water and glass.  Let .C. be the critical angle of interface of glass and water. From the given condition `alpha GT C .......(1)` We KNOW, `sin C=1/(n^(12))` ........(2) `n_(12)=3/2 / 4/3=9/8` From equation 2, we get `sin C=8/9 rArr C=62^(@)30^(1)` Hence `alpha` is greater than `C=62^(@)30^(1)` Let US see few activities of total internal reflection. |
|