If two cells of emfs $\epsilon_1$ and $\epsilon_2$ ($\epsilon_1 \epsilon_2$) are connected in seri

Question

If two cells of emfs $\epsilon_1$ and $\epsilon_2$ ($\epsilon_1 > \epsilon_2$) are connected in series such that their negative terminals are joined together, the equivalent emf is:

Professor PC Thomas Classes · Answer

If the negative terminal of the second cell is connected to the negative terminal of the first, the emfs oppose each other, and the equivalent emf is $\epsilon_1 - \epsilon_2$.