A simple series circuit contains an ideal battery and a single resistor
PHYSICS · Multi-part · CBSE · Physics · Current Electricity · Current Electricity
Problem
A simple series circuit contains an ideal battery and a single resistor. Conventional current flows from the battery’s positive terminal, through the resistor, and back to the battery’s negative terminal. Three labelled points are defined: point A at the negative terminal of the battery, point B at the positive terminal, and point C at the node immediately after the resistor.
Answer the following about the algebraic signs that should be assigned to potential differences when writing an expression for the closed-loop sum of potential changes.
(a) A student begins at point A and moves through the battery to point B while mentally constructing the loop sum. State the sign (positive or negative) that should be written in front of the battery’s potential difference term, and explain your reasoning in terms of the energy change experienced by a positive test charge.
(b) The same traversal continues from point B through the resistor to point C (i.e., in the direction of the current). State and justify the sign that should accompany the resistor’s potential difference in the loop sum.
(c) Suppose a second student instead begins at point C and moves through the resistor toward point B—that is, opposite the current direction—before continuing through the battery back to point C. What sign should now be assigned to the resistor’s potential difference, and why?