A current loop in a magnetic field experiences a turning effect that depends on the angle between its area normal and the field.
Difficulty
Intermediate
Read time
5 min
Prerequisites
Basic algebra, consistent units, and the stated model assumptions
Source
OpenStax, College Physics 2e, §22.8 (Paul Peter Urone and Roger Hinrichs)OpenFormulaGraph equation reference; FormuLab adaptation details and license are provided below.
Adapted from OpenFormulaGraph, under CC BY 4.0.
FormuLab adapted wording, notation, applicability conditions and topic placement, and expanded the numerical check into a worked example. The textbook section reference was corrected.
A current loop in a magnetic field experiences a turning effect that depends on the angle between its area normal and the field. The torque is greatest when those directions are perpendicular.
| Symbol | Meaning | Units |
|---|---|---|
| Torque | ||
| Number of coil turns | ||
| Electric current | ||
| Area enclosed by one turn | ||
| Magnetic Field | ||
| Angle |
Estimate turning effect on a current loop.
Compare torque as the loop rotates in a field.
A 50-turn coil of area 0.0100 m² carries 2.00 A in a 0.300 T field. Its area normal is perpendicular to the field. Find the torque magnitude.
OpenFormulaGraph equation reference; FormuLab adaptation details and license are provided below.
Adapted from OpenFormulaGraph, under CC BY 4.0.
FormuLab adapted wording, notation, applicability conditions and topic placement, and expanded the numerical check into a worked example. The textbook section reference was corrected.
Assumptions
FormuLab is a study reference. Verify formulas, units, assumptions, and course-specific conventions before relying on them.
© 2026 FormuLab. All rights reserved.