Question

a copper wire has diameter 0.5 mm and resistivity of 1.6 into 10 power minus 8 m what will be the length of the wire of neck its resistance 10 how much does the resistance change its the diameter is doubled

Answer 1

cross-section of the wire, A =? (d/2) 2  

Diameter= 0.5 mm = 0.0005 m  

Resistance, R = 10 ?

We know that  

in image

? 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 R?  

now in 2nd image

hence the new resistance is 2.5

A.F