Halliday, Resnick & Walker — Circuits: Problem 4

4 Both batteries in Fig. 27-19a are ideal. Emf \(\mathcal{E}_1\) of battery 1 has a fixed value, but emf \(\mathcal{E}_2\) of battery 2 can be varied between 1.0 V and 10 V. The plots in Fig. 27-19b give the currents through the two batteries as a function of \(\mathcal{E}_2\). The vertical scale is set by \(i_s = 0.40 \text{ A}\). You must decide which plot corresponds to which battery, but for both plots, a negative current occurs when the direction of the current through the battery is opposite the direction of that battery's emf. What are (a) emf \(\mathcal{E}_1\), (b) resistance \(R_1\), and (c) resistance \(R_2\)?