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 smallest possible resistance, you should attach
The leads to the opposite faces that measure
A) $3 \mathrm {~cm} \times 5 \mathrm {~cm}$.
B) $5 \mathrm {~cm} \times 8 \mathrm {~cm}$.
C) $3 \mathrm {~cm} \times 8 \mathrm {~cm}$.
D) Any pair of faces produces the same resistance.

Question

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 smallest possible resistance, you should attach
The leads to the opposite faces that measure 
A) $3 \mathrm {~cm} \times 5 \mathrm {~cm}$.
B) $5 \mathrm {~cm} \times 8 \mathrm {~cm}$.
C) $3 \mathrm {~cm} \times 8 \mathrm {~cm}$.
D) Any pair of faces produces the same resistance.

Quizplus · Accepted Answer

The resistance of a conductor is inversely proportional to its cross-sectional area. Attaching leads to the faces measuring $5 \mathrm{~cm} \times 8 \mathrm{~cm}$ provides the largest cross-sectional area, thus resulting in the smallest resistance.

You Are Given a Copper Bar of Dimensions 3 Cm 3 cm×5 cm3 \mathrm {~cm} \times 5 \mathrm {~cm}3 cm×5 cm

You Are Given a Copper Bar of Dimensions 3 Cm $3 \mathrm {~cm} \times 5 \mathrm {~cm}$