Two metal wires of identical dimensions are connected in series if `sigma_(1)` and `sigma_(2)` are the conductivity of the metal wire respectively the effiective conductivity of the combination is

Options

A. `(sigma _(1) + sigma_(2))/(2 sigma_(1) sigma_(2))`
B. `(sigma_(1) + sigma_(2))/(sigma_(1) sigma_(2))`
C. `(sigma_(1) sigma_(2))/((sigma_(1)+ sigma_(2)))`
D. `(2 sigma_(1) sigma_(2))/(sigma_(1) + sigma_(2))`

Answer

B