Two sources of equal emf are connected to an external resistance R. The internal resistance of the two sources are` R_(1) and R_(2) (R_(1) gt R_(1))`. If the potential difference across the source having internal resistance `R_(2)` is zero, then

Options

A. `R = R_(1)R_(2)//(R_(1)+R_(2))`
B. `R = R_(1)R_(2)//(R_(2)-R_(1))`
C. `R = R_(2) xx (R_(1) +R_(2))// (R_(2)-R_(1))`
D. `R = R_(2) -R_(1)`

Answer

D