A student assembles a series circuit consisting of a single loop containing a DC…
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Electric Circuits · Electric Circuits
Problem
A student assembles a series circuit consisting of a single loop containing a DC power supply, a switch, and three carbon-film resistors whose nominal values are 150Ω, 220Ω, and 330Ω. With the switch closed and the circuit in a steady state, the student records the following potential differences (all measurements are taken with a digital voltmeter, positive probe first):
• Across the power supply: +9.1V
• Across the 150Ω resistor: −1.4V
• Across the 220Ω resistor: −2.1V
• Across the 330Ω resistor: −5.5V
The manufacturer specifies that the meter uncertainty is ±0.1V for readings in this range.
(a) Starting at the negative terminal of the power supply and moving once around the loop in the direction of conventional current, calculate the algebraic sum of the measured potential differences. Express your answer with the correct sign and units.
(b) Using the result from part (a) and the stated meter uncertainty, discuss whether the student’s measurements are consistent with energy conservation in the circuit. Justify your answer quantitatively.
(c) Identify one plausible experimental factor that could account for any lack of agreement with energy conservation, and explain qualitatively how that factor would influence one or more of the recorded readings.