When 115V is applied across a wire that is 10m long and has a 0.30mm radius, the current density is `1.4xx10^(4) A//m^(2)`. The resistivity of the wire is

Options

A. `2.0xx10^(-4)Omegam`
B. `4.1xx10^(-4)Omegam`
C. `8.2xx10^(-4)Omega m`
D. `2.0xx10^(-3)Omegam`

Answer

3

Explanation

V=IR
`=l(rho(l)/(A)) (therefore R=rho(l)/(A))`
`=((l)/(A))rhol`
`V= J rhol (therefore J=(l)/(A))`
Given , `(V)/(Jl)=(115V)/(1.4xx10^(4)A//m^(2)xx10m)`
`=8.2xx10^(-4)Omegam`