A potentiometer wire has a resistivity of `10^(9)Omega` cm and area of cross-section is `10^(-2)"cm"^(2)`. If current of `0.01" mA"` passes through the wire, potential gradient is

Options

A. `10^(9)V//m`
B. `10^(-9)V//m`
C. `10^(8)V//m`
D. `10^(6)V//m`

Answer

C

Explanation

`rho'=10^(9)Omega cm, A=10^(-2) cm^(2), I=0.01m A, (V)/(l)=?`
`V=IR`
`V=I.(rho' l)/(A)`
`:.(V)/(l)=(I rho')/(A)`
`=(0.01xx10^(-3)xx10^(9)xx10^(-2))/(10^(-2)xx10^(-4))=10^(8)V//m`