The animation shows how an electrical voltage is induced in a conductive material via a rotating magnet. The animation thus provides an introduction to the functional principle of electrical generators.

## Note on use

As with all animations, the windows can be enlarged or reduced by clicking on them.

The 3D model can be rotated.

You can enlarge and reduce the rectangles in the animation by clicking with the mouse.

After starting the application, you can view the animation in full-screen mode. To do this, click on “View” and then on “Full screen”:

To exit full screen mode, press the Esc key.

## Explanations

In principle, the induced voltage can be understood as a function of the angular velocity in relation to a specific point in time. In other words, the faster the magnetic field rotates, the higher the induced voltage. The following formula expresses the relationship:

The symbol Û (pronounced “U-hat”) stands for the maximum voltage that can be induced. The sine function expresses the fact that only movement transverse to the direction of the field lines has an influence on the induced voltage. Movements in the direction of the field lines have no influence. The Greek letter ω stands for the angular velocity, which can also be expressed by the following formula:

The letter f stands for the frequency.

Note: Please note that the expression “ωt” in the above formula must not be interpreted as a product. It is simply the angular velocity at time t.

The relationship shown here can also be expressed by the following more basic formula (Faraday’s law of induction)

In this formula, the level of the induced voltage is considered as a function of the magnetic field change (delta Phi divided by delta t) and the number of windings (N). The minus sign has its origin in the historic assumption about the direction of electric currents.

In technical applications, e.g. in classic generators, conductor windings that run around the magnet several times are used instead of a single conductor material.

Note: The animation takes into account the difference between technical and physical current direction. Electrons, indicated by blue spheres, show the physical direction of the current.

The symbolism of the cross and dot refers to the technical current direction.

## Note on use

The 3D model can be rotated.

You can enlarge and reduce the rectangles in the animation by clicking with the mouse.

After starting the application, you can view the animation in full-screen mode. To do this, click on “View” and then on “Full screen”:

To exit full screen mode, press the Esc key.

## Overview and download

Title | Electromagnetic induction through rotation |

Target group | Teachers and lecturers |

Platforms | Microsoft® Windows® Apple® Macintosh® |

Features | Full screen mode lossless zoom Large screens and projection screens supported |

Licence | Freeware |

Download | Contact us |

## Contributors

C. Hein, S. Rikowski

## Source information

- Authoring tool: Adobe Animate
- 3D engine for 3D model: Papervision3D 2.0
- Idea and initial concept: Tamara Riehle
- 3D rotations: Algorithm adopted from Federico Calvo: http://blog.federicocalvo.com/2009/03/papervision-3d-sphere-globla-axis.html

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