A cell sends a current through a resistance `R_(1)` for time `t`, next the same cell sends current through another resistance `R_(2)` for the time `t` If the same amount of heat is developed in both the resistance then find the internal resistance of the cell
A. `r=sqrt(R_(1)+R_(2))`
B. `r=sqrt(R_(1)xxR_(2))`
C. `r=(R_(1)+R_(2))/(2)`
D. `r=(1)/(R_(2))+(1)/(R_(2))`
