Question

A copper wire has a diameter 0.5mm and resistivity 1.6×10-8ohm- m what will be the length if resistance is 10 ohm
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Answer 1

Ans: Area of cross-section of the wire, A =π (d/2) 2

Diameter= 0.5 mm = 0.0005 m

Resistance, R = 10 Ω

We know that

∴ length of the wire = 122.72m

If the diameter of the wire is doubled, new diameter=2×0.5=1mm=0.001m

Let new resistance be Rʹ