Saved Bookmarks
| 1. |
Show that when a light beam is incident on a refractive surface at the polarising angle, the reflected and refracted beams are mutually perpendicular to each other. |
|
Answer» Solution :When a light beam travelling in air is INCIDENT on the surface of a refractive medium of refractive index at the polarising angle `i_(p)`, then according to Brewster.s law `tani_(p)=(sini_(p))/(cosi_(p))=n` If the refracted beam subtends an angle of refraction r in given medium, then according to Snell.s law `(sini_(p))/(sinr)=n` Comparing (i) and (ii), we have `cosi_(p)=sinrimplies sin(90-i_(p))=sinrimplies90-i_(p)=r or r+i_(p)=90^(@)` Then, angle between REFLECTED and refracted (TRANSMITTED) rays `angle RAT=180^(@)-(r+i_(p))=180^(@)-90^(@)=90^(@)` i.e., the reflected and refracted rays are MUTUALLY perpendicular. |
|