Electric Potential (Charged Plane)

AI Thread Summary
The discussion centers on calculating the electric potential at a distance from a charged flat metal plate with a given surface charge density. The initial equation presented for electric potential, V=V0+Ex, is questioned regarding its accuracy in this context. Participants clarify that the electric field E should be derived from the surface charge density, with differing interpretations based on whether the plate is considered thick or thin. The correct formula for the electric field magnitude in the case of a thin plate is |E| = σ/(2ε0). The conversation emphasizes the importance of understanding the geometry of the charged plate in determining the electric potential.
GDGirl
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Teacher explained the solution- thanks!
 
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Hi GDGirl,

GDGirl said:

Homework Statement


The electric potential of a very large flat metal plate is Vo = 69 V. It carries a uniform distribution of charge of surface density σ = 0.29 μC/m2. Determine the electric potential V at a distance x = 3.3 cm from the plate. Consider the point at x to be far from the edges, and assume that x is much smaller than the plate dimensions.


Homework Equations


V=V0+Ex

I don't believe this is quite right. Remember that when you move away from positive charges the potential decreases. Do you see what it needs to be?

E=σ/ϵ0

This could be true, but not the way I read the problem. The formula you have here would be true if they meant that the plate was thick and that each side had σ = 0.29 μC/m2. However, if they meant that the plate was thin, then you would have for the magnitude of the electric field:

<br /> |E| = \frac{\sigma}{2\epsilon_0}<br />

so that might be another problem.
 

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