How polarization takes place?

Answer 1

Light, which is an EM Wave must satisfy maxwells eq. Normally we think that a E-field vibrating in x-axis and H-field vibrating in y axis is the solution to the eqs. This is the case of linear polarization where the E-field is constrained in one plane only. But there are numerous other possibilities too. The E-field might itself rotate continuously (changing planes continuously) with the H-field always remaining perpendicular to it. In this case the tip of the E-vector would look like rotating about z-axis, yet at any instant you find the H-field being perpendicular to the E-field vector and hence satisfying the maxwells eq. This perfectly valid EM wave would then be termed as elliptically polarized. A special case of elliptical polarization is circular polarization. Picture yourself looking right at the direction of light in which it is propagating and imagine the locus of the tip of the E-field vector. If the E-field vector is constrained in one plane then you are going to see a straight line. The light is then said to be linearly polarized. On the other hand if the E-field is rotating with constant magnitude, you would see a circle, and this EMwave is circularly polarized. Elliptical or circular polarization has to be brought about by two em waves interfering with each other. The vector sum of the E-fields can give the net E-field an elliptical shape. .