The length and radius of an electric resistance of a certain wire are doubled simultaneously, then the _.
Correct answer: B. Resistance will be halved and specific resistance will remain unchanged
- A. Resistance will be doubled and specific resistance will be halved
- B. Resistance will be halved and specific resistance will remain unchanged
- C. Resistance will be halved and specific resistance will be doubled
- D. Resistance and specific resistance will both remian unchanged
Explanation
Option B is correct since we know that, R = pl / A = pl / πr2 R' = p2l / / π(2r2) = R / 2 Specific resistance will remain the same as it is a material property but remember it depends on temperature.
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About Resistance and Resistivity
Resistance measures opposition to current in a conductor and follows R = V/I for an ohmic conductor, while resistivity is an intrinsic property of the material. Questions use R = ρL/A, examine effects of length, cross-sectional area and temperature, and distinguish resistance, resistivity, conductance and conductivity.
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