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NEET 1997 (AIPMT) · Ohm's Law, Resistivity & Temperature

Ohm's Law, Resistivity & Temperature question from NEET 1997 (AIPMT)

Q76NEET 1997 · AIPMTMedium

Ohm's Law, Resistivity & Temperature

Three copper wires of lengths and cross-sectional areas are $(l, A),\ (2l, A/2)$ and $(l/2, 2A)$ . Resistance is minimum in

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Answer: (a)

$R = \rho l/A \propto l/A$ .
$(l, A): l/A$ ; $(2l, A/2): 4\,l/A$ ; $(l/2, 2A): \tfrac14\,l/A$ .
Minimum for the wire of area $2A$ . The answer is (a).

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