The resistance between ends will be `(if (rho L)/(pi R^2) = R_0)`
.

Options

A. `(2 R_0)/(7)`
B. `(R_0)/(7)`
C. `(3 R_0)/(7)`
D. `(4 R_0)/(7)`

Answer

A

Explanation

`R_1 = (2 rho L)/(pi R^2) = 2 R_0`
`R_2 = (rho L)/(pi(2 R)^2 - pi R^2) = (rho L)/(3 pi R^2) = (R_0)/(3)`
`R_(eq) = (R_1R_2)/(R_1 + R_2) = (2R_0.(R_0//3))/(2 R_0 + (R_0//3)) = (2 R_0)/(7)`.