When a light is polarized,what happens to its magnetic field?

When unpolarized light goes through a polarizing filter, half of the lights energy is absorbed by the filter (that's the idealized short story). The outcoming light's electric field "oscillates" along one transverse axis. The light's magnetic field still oscillates along along an axis perpedicular to the electric field.

The "picket fence analogy" is usually to blame for this. Polarization of light is not due to light squeezing through tiny gaps in the substance.

 

Light is an electromagnetic wave, which is a disturbance in an electromagnetic field that propagates at a fixed speed.

Most of the light we observe is due to black body radiation, fluroescence can be put down to spontaneous emission, whereas lasers generate light via stimulated emission.

Claude.

 

The flow is discontinuous. The discontinuous flow manifests itself as quantum noise when attempting to detect weak light sources.

Claude.