05:53
@AshishAhuja The reflectivity of light polarised parallel to and perpendicularly to the surface is different. There isn't an intuitive way to understand why this is, or at least I don't know of one.
But it means that if you reflect unpolarised light from the surface then because the reflectivities of the two polarisations are different the reflected light is always polarised to some extent.
At the Brewster angle the reflectivity of light polarised normal to the surface goes to zero, so the only light reflected is light polarised parallel to the surface. So the reflected light is completely polarised parallel to the surface.
@WilliamJohn Yes, the charged spheres polarise each other:
When the spheres are close to each other the charges on them get pulled towards the other sphere so the charge distribution is now not uniform. The charges are on average closer together than they would be if they were evenly distributed, so the force between the spheres is increased.
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