Question

Two wires A and B are made of same material and have the same length but different cross-sectional areas. If the resistance. of wire A is 9 times the resistance of wire B, the ratio of the radius of wire A to that of wire B is?

• A. 3:1
• B. 1:9
• C. 1:3
• D. 9:1

Answer 1

Answer:

C. 1:3

Resistance is inversely proportional to the square of the radius. Given that the resistance of A is 9 times that of B, the radius ratio is √9 = 3, so the radius of A to B is1 : 3.