Two non-ideal unidentical batteries are connected in parallel with positive terminals. Consider the following statements:
A. The equivalent emf is smaller than either of the two emfs.
B. The equivalent internal resistance is smaller than either of the two internal resistances.
Answer & explanation
Correct answer: option 3
$E_{e q}=\frac{E_1 / r_1+E_2 / r_2}{1 / r_1+1 / r_2}=\frac{E_1 r_2+E_2 r_1}{r_1+r_2}=E_1\left[\frac{r_2+r_1\left(E_2 / E_1\right)}{r_1+r_2}\right]$
Therefore, Eeq can be greater than, less than or equal to E1 depending upon the condition whether
E2 > E1, E2 = E1 or E2 < E1