If the length of the conductor is made 4 times its original length, its resistance becomes
Correct answer: D. 4 times
- A. Quarter
- B. Half
- C. Zero
- D. 4 times
Explanation
Resistance is proportional to length for a given cross section and material, so quadrupling the length quadruples the resistance. Note that if the wire were stretched to four times its length at constant volume, the area would fall to a quarter and the resistance would rise sixteenfold, which is the harder variant of this question. Here only the length is stated to change.
This question appeared on the UHS MDCAT 2025 paper, which you can sit online with every answer explained.
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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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