In a metere bridge, the balance length from left end (standard resistance of `1Omega` is in the right gap) is found to be 20 cm, the length of resistance wire in left gap) is found to be 20 cm the length of resistance wire in left gap is `(1)/(2)` m and radius is 2mm its specific resistance is

Options

A. `pixx10^(-6)ohm-m`
B. `2pixx10^(-6)ohm-m`
C. `(pi)/(2)xx10^(-6)ohm-m`
D. `3pixx10^(-6)ohm-m`

Answer

B

Explanation

`X=(sl)/(A)`
`(X)/(R)=(20)/(80)`
`(1)/(4)=(Sxx(1)/(2))/(pixx(2xx10^(-3))^(2))`
`X=(Rxx2)/(8)`
`X=(1)/(4)`
`S=2pixx10^(-6)Omega-m`