Question

How does a polarizing filter work? After passing through a polarizing filter that is aligned vertically, how are the electric and magnetic fields of the EM waves aligned? If you wished to block the light completely, how would you align a second polarizing filter that was placed directly behind the first?

Answer 1

A polarizing filter is basically a device that helps in removing or eliminating all the planes of vibration of the wave except the one which is aligned along the passage of the polarizing filter. The filter when aligned in a particular orientation allows only the vibrational plane along its alignment to pass and hence the intensity of light gets reduced on the other side of the filter.

After passing through a vertical filter the electric field is aligned vertically while the magnetic field is aligned towards left when viewed from the other side of the polarizing filter this is because the light coming out of polariser is moving forward with vibrational plane in vertical direction.

For complete blocking of light the other polarizer should be kept perpendicular to the first one because the intensity coming out of a polariser - analyser arrangement is directly proportional to the cosine of angle between the two of them.