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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?

A3:1

B1:9

C1:3

D9:1

Answer:

C. 1:3

Read Explanation:

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.


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