# Electric Fields Lines of a pair of Finite Parallel Plates

## Homework Statement

Comment on the electric field lines of a pair of finite parallel plates (a) between the plates and (b) near the edges of the plates.

## The Attempt at a Solution

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between the plates (basically near centers of plates) in is uniform, directed from + plate to - plate (obvious)
magnitude is double the mag due to any 1 plate

near the edge it will be non uniform

"magnitude is double the mag due to any 1 plate"
I don't understand this. Why is that so?

Also, is it correct to say that
(a) between the plates the distribution of charges will be uniform due to its flat nature, but (b) on the edges of the plates the distribution of charges will not be uniform because alone sharp edges charges tend to come together more closely than they typically do on a smooth surface

The magnitude is double because the electric field follows superposition and you have a plate that is positively charged (electric field outward) and a plate that is negatively charged (electric field inward).

I know that the fringing field is non-linear but I've never understood the flux density thing since there can be an infinite amount but the lines can't cross. I just can't visualize it so I stick with the results of the equations...

Also, is it correct to say that
(a) between the plates the distribution of charges will be uniform due to its flat nature, but (b) on the edges of the plates the distribution of charges will not be uniform because alone sharp edges charges tend to come together more closely than they typically do on a smooth surface
in a way you are right
This phenomena is called "corona discharge"
according to it ... charge 'density' is inversely proportional to the radius of surface.
the charge density will be more on th edges but on any flat surface will be same.

can you tell where "charge" will be maximum ????