A series circuit contains an ideal battery of unknown emf E, a 15 Ω resistor R1, a 25 Ω resistor R2, and ideal wires. Beginning at the negative terminal of the battery (point A) and moving clockwise, the electric potential along the loop is measured as follows.
• Segment AB: vertical rise of magnitude E.
• Segment BC: linear drop of 4.5 V.
• Segment CD: horizontal segment of constant potential.
• Segment DE: linear drop of 7.5 V.
• Segment EA: horizontal segment returning to 0 V.
A current probe indicates 0.30 A flowing clockwise through the circuit.
(a) Determine the emf E of the battery.
(b) Show quantitatively that the measured potential drops across R1 and R2 are consistent with the indicated current and the labeled resistor values.
(c) Explain how the orientation of the potential–position graph indicates the direction of conventional current in the loop.
(d) Calculate the total power delivered by the battery and compare it with the total power dissipated by both resistors, commenting on any difference.