How can E&M Waves be polarized?

[astromajor]

I'm learning about polarization and something has me a little confused. I feel like I understand polarization: blocking out all the light except for those waves in a particular direction: horizontal, vertical, e.g. But if a "single" light wave is made of a propagating electric and magnetic field, which are perpendicular to each other, how can you just block out one of those directions? If you blocked the direction the magnetic wave was traveling, for example, wouldn't that cease the electric portion as well and therefore no light would get through? Thanks for your help!

 

[cepheid]

I'm learning about polarization and something has me a little confused. I feel like I understand polarization: blocking out all the light except for those waves in a particular direction: horizontal, vertical, e.g. But if a "single" light wave is made of a propagating electric and magnetic field, which are perpendicular to each other, how can you just block out one of those directions? If you blocked the direction the magnetic wave was traveling, for example, wouldn't that cease the electric portion as well and therefore no light would get through? Thanks for your help!

By definition, polarization describes the direction in which the E-field points. Blocking out horizontal polarization means blocking out light waves whose E-fields oscillate horizontally, leaving only light waves whose E-fields oscillate vertically. It's always a given that the B-field is perpendicular to the E-field for a given polarization state. Therefore, mentioning the B-field direction is redundant/unnecessary.