Resistivity of iron is 1 x 10^-7 ohm-metre. The resistance of the given wire of a particular thickness and length is 1 Ω. If the diameter and length of the wire both are doubled, the resistivity will be :
Correct answer: A. 1 x 10^-7
- A. 1 x 10^-7
- B. 2 x 10^-7
- C. 4 x 10^-7
- D. None of these
Explanation
Resistivity is a fundamental property of a material, unaffected by changes in the physical dimensions of a wire, such as its length or diameter. It is dependent only on the material's intrinsic properties and temperature. Therefore, even if the length and diameter of the wire are doubled, the resistivity remains at 1 × 10-7 ohm-meter. The other options incorrectly imply that resistivity changes with geometric dimensions, which is not the case.
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