Refer to the multi-branch circuit shown in the figure. Using the source polarities and resistor values shown there, what are the potential difference V(A)-V(B) and the current through the external branch between A and B?

Question

G1 Physics · Accepted Answer

Using the parallel source branches shown in the figure, their Thevenin equivalent between A and B has E(eq) = 27 V and r(eq) = 3 ÷ 4 Ω. The external branch between A and B has resistance R = 6 Ω. Hence the current through the external branch is I = E(eq) ÷ [R+r(eq)] = 27 ÷ [6+3 ÷ 4] = 27 ÷ (27 ÷ 4) = 4 A. Therefore the terminal potential difference is V(A)-V(B) = IR = 4×6 = 24 V. Correct option: B.