You are given a copper bar of dimensions 3 cm × 5 cm × 8 cm and asked to attach leads to it in order to make a resistor. If you want to achieve the largest possible resistance, you should attach
The leads to the opposite faces that measure
A) 3 cm × 8 cm.
B) 5 cm × 8 cm.
C) 3 cm × 5 cm.
D) Any pair of faces produces the same resistance.

Question

Quizplus · Accepted Answer

Resistance is directly proportional to the length of the conductor and inversely proportional to its cross-sectional area. Attaching the leads to the opposite faces measuring 3 cm × 5 cm makes the length of the conductor 8 cm (the longest possible length) and the cross-sectional area the smallest possible (15 cm²), resulting in the highest resistance.

You Are Given a Copper Bar of Dimensions 3 Cm