일반물리학 2 — Circuits: Problem 27

27 In Fig. 27-36, battery 1 has emf $\mathcal{E}_1 = 12.0 \text{ V}$ and internal resistance $r_1 = 0.025 \ \Omega$ and battery 2 has emf $\mathcal{E}_2 = 12.0 \text{ V}$ and internal resistance $r_2 = 0.012 \ \Omega$. The batteries are connected in series with an external resistance $R$. (a) What $R$ value makes the terminal-to-terminal potential difference of one of the batteries zero? (b) Which battery is that?