- Brewster’s law is based in the polarization of light by reflection.
- Polarization is the phenomenon of in which vibrations of light waves are restricted in a plane which is perpendicular to the direction of wave motion.
- The light in which the vibrations of all electric vectors is in all possible directions perpendicular to the direction of propagation is called as unpolarized light.
- The light in which electric vectors are vibrating only in one plane and whose direction is perpendicular to the direction of propagation is called as plane polarized light.
Statement:
Brewster’s law states that, the tangent of the polarising angle ip is always must be equal to the refractive index of the medium where partial reflection is occurring.
Contents
Mathematically,
μ = tanip
Were,
μ is the refractive index of the medium
And ip is the polarising angle
Explanation:
Brewster’s law states that, the tangent of the polarising angle ip is always must be equal to the refractive index of the medium where partial reflection is occurring.
Mathematically,
μ = tanip
Were,
μ is the refractive index of the medium
And ip is the polarising angle
- When we incident the light on the transparent medium at an angle of polarization then it was observed that the reflected light is completely polarized which is in the plane of incidence and the refracted ray is partially polarized as shown in following figure.
- And here the reflected and refracted rays make angle 90° with each other.
- Then in above situations, tangent of the angle of polarization is found numerically equal to the refractive index of the medium.
- Thus, it is proved that polarizing angle depends on the wavelength and hence it is different for different colours also.
- And Brewster’s law is not applicable or not hold good for polished metallic surfaces also.