Question

Calculate the resistance of a copper wire 1.0 km long and 0.50 mm diameter if the resistivity of copper is 1.7×10−8ωm.​

Answer 1

l=1km=1000m

d=0.50,r=0.50/2 = 0.25

resistivity= 1.7*10-8

area=πr^2=3.14*(0.25)^2

=3.14*0.0625

=19.625 mm

=19625/1000*1000m

now, resistivity = Resistance*area/length

resistivity*length/area=resistance

1.7*10-8*1000*1000*10000/19625=R

R=0.000866242Ohm