- #1

rudransh verma

Gold Member

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In this page you can see it’s written: E must be perpendicular to the surface. If it were not then the charges would move due to a component along the surface.

I am assuming the field is generated due to the charges on the surface.

I have a doubt. Is the author saying if it were not perpendicular then some charges would leave the surface.

Because maybe the field is not actually perpendicular. That’s why the surface charge density is not same everywhere. Some of the field vectors are not perpendicular and due to that some charges shift from their place and we get uneven charge density.

I don’t understand one more line below: we assume that the cap area A is small enough so that the field Magnitude E is constant…

So that means Es magnitude is changing over the entire surface because of the varying charge density. Some places there is more charge so E produced is more and vice versa. The area A we are considering has the same charge density everywhere in it and so is E in that area.

I am assuming the field is generated due to the charges on the surface.

I have a doubt. Is the author saying if it were not perpendicular then some charges would leave the surface.

Because maybe the field is not actually perpendicular. That’s why the surface charge density is not same everywhere. Some of the field vectors are not perpendicular and due to that some charges shift from their place and we get uneven charge density.

I don’t understand one more line below: we assume that the cap area A is small enough so that the field Magnitude E is constant…

So that means Es magnitude is changing over the entire surface because of the varying charge density. Some places there is more charge so E produced is more and vice versa. The area A we are considering has the same charge density everywhere in it and so is E in that area.

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