What's the Resistance in a Circular Pan with a Metal Disk?

AI Thread Summary
The problem involves calculating the resistance of a circular pan with a metallic side wall and a central metal disk, filled with a resistive solution. The resistance is determined using the formula R = pL/A, where p is resistivity, L is the length, and A is the cross-sectional area. To find the total resistance, one must consider the resistance of thin rings between the disk and the pan's edge. The final expression for resistance is given as (p*ln(b/a))/(2πL). Understanding the combination of these rings is crucial for solving the problem effectively.
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Homework Statement



A circular pan of radius b has a plastic bottom and metallic side wall of height h. It is filled with a solution of resistivity p. A metal disk of radius a and height h is placed at the center of the pan. The side and disk are perfect conductors. what's the resistance measured from the side of the disc. the answer is suppose to be (p*ln(b/a))/(2'pie'L)

Homework Equations



R= pL/A

The Attempt at a Solution


I kinda don't know how to start. the solution makes me confused
 
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What would be the resistance of a thin ring, with height h, radius r, and thickness Δr?

Once you get that, think of how to combine many such rings to fill the space between r=a and r=b.
 

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