A student is asked to analyze the current in a closed circuit consisting of a single…
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Electric Circuits · Electric Circuits
Problem
A student is asked to analyze the current in a closed circuit consisting of a single 12 V battery and two resistors in series. The student’s written response includes the following statement and diagram snippet:
“Because electrons are negatively charged, the current in this circuit travels from the negative terminal through the resistors toward the positive terminal.”
In the diagram snippet, arrows on the wires point from the negative terminal of the battery toward the positive terminal, and the student has labeled these arrows “current.”
(a) Identify and explain the conceptual error in the student’s statement and diagram regarding current direction.
(b) Redraw the portion of the diagram showing the correct direction of conventional current and, using a different style of arrow, also indicate the electron drift direction.
(c) Provide a concise explanation suitable for a peer that reconciles the existence of two opposite arrow conventions while preventing future confusion between them.
(d) Suppose the resistors are exchanged for identical lightbulbs. Predict how, if at all, the incorrect current direction indicated by the student would affect qualitative predictions about bulb brightness, and justify your answer.