Question

A copper wire has a diameter of 0.5mm and resistivity 1.6×10^-8 ohm m.
1. What will be the length of the wire to make the resistance of 12 ohm?
2.how much will be the resistance of another copper wire of same length but half the diameter?

Answer 1

Answer:

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