---
title: "Magnetic Flux, Flux Linkage and Faraday's Law"
description: "Flux is the amount of field passing through an area, and flux linkage counts that once for every turn of a coil. The induced emf is equal to the rate at which the linkage changes."
canonical: https://lightmysky.com/learn/science/magnetic-flux-flux-linkage-and-faradays-law-mt_ZoN5JePCpt
source: https://lightmysky.com/learn/science/magnetic-flux-flux-linkage-and-faradays-law-mt_ZoN5JePCpt.md
retrieved: 2026-09-12
---

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# Magnetic Flux, Flux Linkage and Faraday's Law

Flux is the amount of field passing through an area, and flux linkage counts that once for every turn of a coil. The induced emf is equal to the rate at which the linkage changes.

Subject: Science · Area: Energy · Ages 17 to 18
Page: https://lightmysky.com/learn/science/magnetic-flux-flux-linkage-and-faradays-law-mt_ZoN5JePCpt

## Ready when they can

- Calculates flux as BA cos theta and flux linkage as the number of turns times the flux
- Finds an induced emf from the gradient of a flux linkage against time graph
- Explains why a coil turning in a steady field still has a changing linkage

## Lesson: Flux today, emf tomorrow

Flux is the field threading a loop: B A cos theta, where theta tilts between the field and the loop normal. Edge on, the flux vanishes even in a strong field. With N turns, linkage is N times the flux. Forgetting the tilt or the turn count causes most errors.

Faraday says induced emf equals the rate of change of linkage, with a sign for Lenz. Read emf off the gradient of a linkage against time graph: steep means big emf, flat means none. A linkage falling from 10 to 2 in 4 seconds gives an emf of 2 volts.

A coil turning in a steady field still sees changing linkage, since its projected area swings with the angle. That swing is the heartbeat of every generator. Spin faster, add turns, strengthen the field, or enlarge the area to raise the emf.

**Recap.** Count field times area times turns, price change as emf, and spin the coil to keep it changing.

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [Electromagnetic Induction and Generators](https://lightmysky.com/learn/science/electromagnetic-induction-and-generators-mt_e0jgUKANT-)
- [Charged Particles Moving in a Magnetic Field](https://lightmysky.com/learn/science/charged-particles-moving-in-a-magnetic-field-mt_evuhZ6cSfI)

## Opens up

- [Lenz's Law and the Alternating-Current Generator](https://lightmysky.com/learn/science/lenzs-law-and-the-alternating-current-generator-mt_69u-fTOSku)