Question

A aluminium wire has a diametre of 0.5 mm and resistivity 2.8*10^-6 ω cm. how much length of wire is required to make a coil of 10 ω

Answer 1

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



∴ the new resistance is 2.5 Ω