PhysicsMagnetism and InductionUniversity

Ampere's Law Calculator

Relates magnetic circulation around a closed path to enclosed steady current.

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Overview

Relates magnetic circulation around a closed path to enclosed steady current. It is content-only because the displayed integral or circulation law is a decision rule before choosing a specific geometry.

Apply it well

When To Use

When to use: Use this to decide which source, path, or geometry controls the magnetic or induced-electric field.

Why it matters: It explains where the simpler magnetic-field formulas in this batch come from.

Avoid these traps

Common Mistakes

  • Treating an integral law as a one-line scalar calculator.
  • Ignoring path orientation or enclosed current/flux.

One free problem

Practice Problem

In the integral expression for Ampere's Law, what does the circle on the integral sign signify regarding the path of integration?

Solve for:

Hint: Consider the geometric requirement for a circulation law.

The full worked solution stays in the interactive walkthrough.

References

Sources

  1. Moebs, Ling, and Sanny, University Physics Volume 2, OpenStax, 2016, chapter 12, accessed 2026-04-09
  2. Wikipedia: Ampère circuital law (accessed 2026-04-09)
  3. NIST CODATA Value of the Vacuum Permittivity
  4. IUPAC Gold Book: Ampere's Law
  5. Wikipedia: Ampère's circuital law
  6. Introduction to Electrodynamics by David J. Griffiths
  7. Feynman Lectures on Physics, Vol. II
  8. NIST Digital Library of Mathematical Functions, Section 28.1