Consider a thin square sheet of side L and thickness t made of a material of resistivity rho. The resistance measured between two opposite faces (the shaded areas) is

directly proportional to L
directly proportional to t
independent of L
independent of t

Correct answer: independent of L

Solution

R = rho*L/(L*t) = rho/t, which does not contain L, so the resistance is independent of L (and inversely proportional to t).

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