The force between charged parallel disks, when distance isn't given?

AI Thread Summary
The discussion focuses on calculating the force between two charged parallel disks with given charge densities and area, while the distance between them is not specified. The electric field generated by each disk can be determined using Gauss's Law, which states that E = charge density / (2 * permittivity of space). Since the electric field is uniform between the plates, the force exerted by one disk on the other can be calculated using the formula F = qE, where q is the charge on one disk. The key point is that the uniform electric field allows for straightforward application of these principles despite the lack of distance information. Understanding the relationship between charge density, electric field, and force is essential for solving this problem.
Allenlbq
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Two circular disks, each of area 2.10×10-4 m2, are situated parallel to one another. The distance between them is small compared with their radii. Both disks are uniformly charged; their charges per unit area are σ = 5.10×10-5 C/m2 for one and -σ = -5.10×10-5 C/m2 for the other. Compute the force exerted by one on the other.

Hint: You can assume the field from each plate to be that of an infinite sheet.

Correct me if I'm wrong, but I believe the electric field is calculated using Gauss's Law : E=(charge density)/(2*permittivity of space). But, how in the world do you get the force exerted by one on the other if distance isn't given?
 
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the E-field is _uniform_ from + plate to - plate. This means that the E-vectors do not spread, so Gauss is really easy to use. F = qE , like always. (how else would you EVER calculate electric Force?)
 

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