Question #56177

1 Answer
Nov 10, 2016

See proof below

Explanation:

The resistance of the first wire is R=rhol/aR=ρla
where rho=ρ= resistivity for this material
l=l=length
a=a=area =pir^2=πr2 where r is the radius

New length =l/2=l2

New radius =r/2=r2

The second wire R_1=rho*(l/2)/(pir^2/4)R1=ρl2πr24

=(4rhol)/(2pir^2)=(2rhol)/(a)=2R=4ρl2πr2=2ρla=2R

So the new resistance is twice the other resistance