1. The problem statement, all variables and given/known data When the resistor is R1, in the circle there is the intensity I1 and when the resistor is R2, the intensity becomes I2.Find emf and the inner resistance. 2. Relevant equations I=emf/R+r 3. The attempt at a solution I1=efm/R1+r I2=efm/R2+r efm is equal I1*(R1+r)=I2(R2+r) r=(I2R2-I1R1)/(I1-I2) And how can I find emf?