일반물리학 2 — Circuits: Problem 44

44 Figure 27-45 shows a section of a circuit. The resistances are $R_1 = 2.0 \Omega$, $R_2 = 4.0 \Omega$, and $R_3 = 6.0 \Omega$, and the indicated current is $i = 9.0 \text{ A}$. The electric potential difference between points $A$ and $B$ that connect the section to the rest of the circuit is $V_A - V_B = 78 \text{ V}$. (a) Is the device represented by “Box” absorbing or providing energy to the circuit, and (b) at what rate?