Current Electricity and Electrical InstrumentHard
Question
Three copper wires of lengths and cross sectional areasare (l,A), (2l,A/2) and(l/ 2,2A). Resistance is minimum in
Options
A.wire of cross -sectional area A/2
B.wire of cross - sectional area A
C.wire of cross - sectional area 2A
D.same in all the three case
Solution
R ∝ 
;
So, the resistance of the wire will be minimum when the area of cross-section is maximum and length is minimum
;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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