A cell develops the same power across two resistances `R_(1)` and `R_(2)` separately. The internal resistance of the cell is

Options

A. `sqrt(R_(1)R_(2))`
B. `sqrt(2R_(1)R_(2))`
C. `R_(1)+R_(2)`
D. `R_(1)-R_(2)`

Answer

A

Explanation

`P_(1)=i^(2)R_(1)=((E)/(R_(1)+r))^(2)R_(1)`
`P_(2)=i^(2)R_(2)=((E)/(R_(2)+r))^(2)R_(2)`