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When 115V is applied across a wire that ...

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

A

`2.0xx10^(-4)Omegam`

B

`4.1xx10^(-4)Omegam`

C

`8.2xx10^(-4)Omega m`

D

`2.0xx10^(-3)Omegam`

Text Solution

Verified by Experts

The correct Answer is:
3
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`
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