---
title: "Two students use Kirchhoff’s loop rule to write an equation for a single closed loop containing an ideal battery of emf \\(\\varepsilon\\) and two resistors of resistance \\(R_1\\) and \\(R_2\\). Student 1 traverses the loop in the clockwise direction, which aligns with the direction of conventional current, and records the potential difference across each resistor as \\(-IR\\). Student 2 traverses the identical loop in the counterclockwise direction, opposite to the conventional current, and records the potential difference across each resistor as \\(+IR\\). Which of the following statements provides the correct physical justification for whether both students can obtain the correct current?"
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url: "https://nerd-notes.com/ubq/120392/"
date_modified: "2026-08-23T04:34:26+00:00"
---

# Two students use Kirchhoff’s loop rule to write an equation for a single closed loop containing an ideal battery of emf \(\varepsilon\) and two resistors of resistance \(R_1\) and \(R_2\). Student 1 traverses the loop in the clockwise direction, which aligns with the direction of conventional current, and records the potential difference across each resistor as \(-IR\). Student 2 traverses the identical loop in the counterclockwise direction, opposite to the conventional current, and records the potential difference across each resistor as \(+IR\). Which of the following statements provides the correct physical justification for whether both students can obtain the correct current?

Two students use Kirchhoff's loop rule to write an equation for a single closed loop containing an ideal battery of emf \(\varepsilon\) and two resistors of resistance \(R_1\) and \(R_2\). Student 1 traverses the loop in the clockwise direction, which aligns with the direction of conventional current, and records the potential difference across each resistor as \(-IR\). Student 2 traverses the identical loop in the counterclockwise direction, opposite to the conventional current, and records the potential difference across each resistor as \(+IR\). Which of the following statements provides the correct physical justification for whether both students can obtain the correct current?

![A single rectangular circuit schematic in the plane of the page. The top horizontal wire contains an ideal battery of emf \(\varepsilon\), oriented with the longer vertical line on the left and the shorter vertical line on the right. The right vertical branch contains a resistor labeled \(R_1\). The bottom horizontal wire contains a resistor labeled \(R_2\). The left vertical branch is a straight connecting wire. A curved clockwise arrow labeled \(I\) is centered inside the rectangle to indicate the direction of conventional current. No other labels, lines, text, or circuit elements appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1787459666-tiSQrj.jpg)

- **A.** Student 1 is correct and Student 2 is incorrect because the loop rule represents conservation of energy along the actual physical trajectory of moving charge carriers.
- **B.** Both students are correct because electric potential is a unique scalar value at each point in the circuit, so traversing against the current measures an increase in electric potential and yields a mathematically equivalent equation.
- **C.** Student 1 is correct and Student 2 is incorrect because electrical energy is dissipated as thermal energy in a resistor, requiring the potential term for every resistive element to always be negative.
- **D.** Both students calculate the correct current magnitude, but Student 2 calculates a current with the incorrect physical direction because traversing against the current reverses the direction of the total loop current.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/120392/*