If the angle of incidence and angle of emergence of a light ray falling on a glass slab are I and e respectively, prove that,i=e.

If the angle of incidence and angle of emergence of a light ray fallin

1.	If the angle of incidence and angle of emergence of a light ray falling on a glass slab are I and e respectively, prove that,i=e.
Answer» Solution :As shown in the figure a ray of light AN is incident on glass and gets REFRACTED. 1. The FIRST refraction OCCURS when light ray enters the glass from air at N on the side PQ. The second refractionoccurs when light enters air through glass at point M on the side SR. The emergent ray is MD. For the first refraction usingSnell's LAW `n_(1) "sin" i=n_(2)` sin r ....(i) 2. Where `n_(1)` is the refractive index of first medium (air) and `n_(2)` is the refractive index of second medium (glass) 3. For the second refraction using Snell's Law `n_(2) "sin" i_(1)=n_(2)` sin e ... (ii) But `i_(1)=r` 4. `n_(2) "sin" r=n_(1)` sin e `""`... (iii) From (i) and (iii) `n_(1) "sin" i=n_(1)` sin e , sin i=sin e Comparing both sides i=e