An electricity and magnetism problem by Amit Kumar
Electricity and Magnetism
Level
2
A copper wire has resistance 0.6 ohm.another copper wire of same mass as the first one is double the length of the first.find the resistance of second wire in ohms.
The answer is 2.4.
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1 solution
SINCE THE VOLUME REMAINS SAME IN BOTH CASES. A * L = A' L' L' = 2L A' = A/2
R' = PL'/A' = 4PL/A = 4R 4 * .6 = 2.4 OHMS
FORMULA FOR THESE TYPE OF QUESTION = R' = N^2R WHERE N IS THE CHANGE IS THE CHANGE IN LENGTH.