An ideal transformer’s voltage ratio equals its turns ratio.
Difficulty
Intermediate
Read time
5 min
Prerequisites
Basic algebra, consistent units, and the stated model assumptions
Source
OpenStax, College Physics 2e, §23.7 (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.
An ideal transformer’s voltage ratio equals its turns ratio. A larger secondary winding raises the voltage magnitude while an ideal transformer conserves transferred power through a corresponding current change.
| Symbol | Meaning | Units |
|---|---|---|
| Secondary RMS voltage | ||
| Primary RMS voltage | ||
| Secondary turns | ||
| Primary turns |
Estimate ideal secondary RMS voltage.
Compare ideal winding configurations.
An ideal transformer has 500 primary turns, 100 secondary turns, and primary RMS voltage 120 V. Find the secondary RMS voltage.
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.