Two wires of the same dimensions but resistivities `rho_(1)` and `rho_(2)` are connected in series. The equivalent resistivity of the combination is

Options

A. `rho_(1) + rho_(2)`
B. `(rho_(1) + rho_(2))/2`
C. `sqrt(rho_(1).rho_(2))`
D. `2(rho_(1) + rho_(2))`

Answer

B

Explanation

`R_(eq) = R_(1) + R_(2) rArr rho(2l)/A = (rho_(1)l)/A + (rho_(2)l)/A rArr rho = (rho_(1)+ rho_(2))/2`