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A wire of a certain material is stretched slowly by ten percent. Its new resistance and specific resistance become respectively

Asked in CBSE AIPMT 2008 · Resistance of a wire and stretching

• (1) both remain the same
• (2) 1.1 times, 1.1 times
• (3) 1.2 times, 1.1 times
• (4) 1.21 times, same

Step-by-step solution

Why the other options are wrong

• (1) Confuses resistance with resistivity; only resistivity is fixed by the material.
• (2) Takes the length-only factor 1.1 for R and then wrongly scales the resistivity too.
• (3) Rounds 1.1² to 1.2 and wrongly scales the resistivity with the length.

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