Electric current > Conductivity. Resistance. Sources of electromotive force > Problem 8.2.22

Statement

$8.2.22.$

Where on the lower and upper surfaces of a round conducting plate should
electrical contacts be placed so that the resistance between them is minimal?

Solution

The resistance between two points on a conducting plate depends on how far the current has to travel.

If you place the contacts facing each other at the center of each face, the path the current takes is the shortest possible because it simply goes straight through the thickness of the plate.

Therefore, the resistance is minimal when the contacts are located exactly at the center of each face.

Answer

$\boxed{\text{The contacts must be placed at the center of the plate from opposite sides.}}$