An aluminium wire carrying a current has diameter `0.84 mm`. The electric field in the wire `0.49 V//m`. What is
(a) the current carried by the wire?
(b) the potential difference between two points in the wire `12.0 m` apart?
(c) the resistance of a `12.0 m` length of this wire?
Specific resistance of aluminium is `2.75 xx 10^-8 Omega -m. `

Answer

A, B, C

Explanation

a. In 1m, potential difference
`V=0.49:. V=iR`
`:. i=0.49/R=((0.49)A)/(rhol)`
`((0.49)(pi//4)(0.84xx10^-3)^2)/((2.75xx10^-8)(1))`
`=9.9A`
b. PD between two points 12 m apart
`=(0.49 V/m)(12m)=5.88V`
c. `R=V/i=5.88/9.9=0.6Omega`