# Sheet of charge - theory

• Iamconfused123
Iamconfused123
Homework Statement
..
Relevant Equations
EA=Q/Eo, Sigma=Q/A, E=kQ/r^2
To some of these questions I can't find answers on the internet and to some I assume what the answer is but I'd still like to get a confirmation.

When I am not given the thickness of the plate, does that mean that the plate is intinitely thin?

What is the area of the sheet of charge when the sheet stands alone when we calculate sigma=Q/A, is it the surface area of both sides of the sheet or just one side?

What is the area in sigma=Q/A when we have a plate next to another parallel plate of opposite charge ( I assume for this one area to be only one side, but still)? In this case what area do we put in formla for Gaussian surface (EA=Q/Eo), because when two plates of opposite charges are next to each other then positive and negative charges on the same plate separate and the extra (for example of positive charge) eminate field only to the right, for example (or do they, I am not sure about this one), so should the area of the Gaussian surface be halved as well?

How does charge distribute itself over infinitely thin sheet? Is area for sigma=Q/A here only one side or both sides?

If charge does not reside IN the conductor but only on the outer surface, do we take only the surace area into account for charge distribution of the capacitor or do we care about volume?

Thank you very much.

Iamconfused123 said:
When I am not given the thickness of the plate, does that mean that the plate is intinitely thin?
Either arbitrarily thin or, for the question asked, the thickness won't matter.
Iamconfused123 said:
What is the area of the sheet of charge when the sheet stands alone when we calculate sigma=Q/A, is it the surface area of both sides of the sheet or just one side?
If Q is the whole charge and ##\sigma## is the density on each side then A is the total area for the two sides.
Iamconfused123 said:
What is the area in sigma=Q/A when we have a plate next to another parallel plate of opposite charge ( I assume for this one area to be only one side, but still)?
If the arrangement ensures all the charge is on the same side then clearly A is just the area of that side.
Iamconfused123 said:
In this case what area do we put in formla for Gaussian surface (EA=Q/Eo), because when two plates of opposite charges are next to each other then positive and negative charges on the same plate separate and the extra (for example of positive charge) eminate field only to the right, for example (or do they, I am not sure about this one), so should the area of the Gaussian surface be halved as well?
I'm not sure I have understood the situation. Please give a specific example.
Iamconfused123 said:
How does charge distribute itself over infinitely thin sheet? Is area for sigma=Q/A here only one side or both sides?
No sheet is infinitely thin. It can be arbitrarily thin.
Iamconfused123 said:
If charge does not reside IN the conductor but only on the outer surface, do we take only the surace area into account for charge distribution of the capacitor or do we care about volume?
Not volume, which would be the product of surface area and plate separation. Instead, it is the ratio of the two that matters.

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