Question

A copper wire has diameter 0.5 m and 20 with 7.6 x 10 - 8 ohm metre what will be the length of this wire to meet its resistance 10 ohm how much does the resistance change if diameter is doubled

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