When ordinary light is reflected from the surface of transparent medium like glass or water it becomes partly polarized. The degree of polarization changes with the angle of incidence. At a particular angle of incidence the reflected light has the greatest percentage of polarized light .The angle at which the reflected light is completely plane polarized, is known as angle of polarization. According to Brewster’s law of angle of polarization is numerically equal to the “tangent Θi refractive index µ of the medium”. µ= tan Θi From Brewster’s law µ= tan Θi------(i) From law µ=sin sin r---------(ii) (where r is angle of refraction) Θi/ tan sin sin r Θi= Θi/ sinr= cos Θi----------------(iii) From fig. r+ 180 -------(iv) (where is angle between reflected ray and refracted Θi+Θ= Θ ray) From equation (iii) sin r=sin(90-Θi) sin r=sin(90-Θi) r= 90-Θi r+ Θi=90----------(v) From equation (iv) and equation (v)
When ordinary light is reflected from the surface of transparent medium like glass or water it becomes partly polarized. The degree of polarization changes with the angle of incidence. At a particular angle of incidence the reflected light has the greatest percentage of polarized light .The angle at which the reflected light is completely plane polarized, is known as angle of polarization. According to Brewster’s law “tangent of angle of polarization Θi is numerically equal to the refractive index µ of the medium”. µ= tan Θi From Brewster’s law µ= tan Θi------(i) From law µ=sin Θi/ sin r---------(ii) (where r is angle of refraction) tan Θi= sin Θi/ sin r sinr= cos Θi----------------(iii) From fig. r+ Θi+Θ= 180 -------(iv) (where Θ is angle between reflected ray and refracted ray) From equation (iii) sin r=sin(90-Θi) sin r=sin(90-Θi) r= 90-Θi r+ Θi=90----------(v) From equation (iv) and equation (v)
be-201-engineering-physics-unit-2.docx