Three copper wires of lengths and cross sectional areas are $(l,\,A),\,(2l,\,A/2)$ and $(l/2,\, 2A)$ . Resistance is minimum in
Awire of cross-sectional area $A/2$
Bwire of cross-sectional area $A$
Cwire of cross-sectional area $2A$
D
same in all the three cases
AIIMS 2013,AIPMT 1997, Easy
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Cwire of cross-sectional area $2A$
c $R\, \propto \,\frac{l}{A}$ ;
So, the resistance of the wire will be minimum when the area of cross-section is maximum and length is minimum.
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