The interactive animation shows how electric current is generated by motion. In the upper left area of the animation, a 3D scene is displayed, consisting of a horseshoe magnet and a metal cylinder (conductor). The conductor can be moved interactively through a magnetic field. In this case, the law of induction predicts the formation of an electric field inside the conductor. Inside the metal cylinder, blue spheres indicate the electric current.
Instructions for Use
The windows can be enlarged or reduced by clicking on them, just like with all animations.
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.
Description of the Animation
The animation shows a 3D model with a horseshoe magnet in the upper left window. Inside the magnetic field is a cylindrical conductor. The electrons are represented by blue spheres.
The magnetic field of the horseshoe magnet can be shown or hidden as needed.
In the upper right window, the objects are shown in a profile view. In this view, the conductor can be moved with the mouse.
The law of induction predicts that electrons start to move when the material is shifted at a 90-degree angle to the field lines of the magnetic field.
\[ U_\text{ind} = – \frac{\Delta \Phi}{\Delta t} \]
The law of induction can also be expressed by the following formula, which describes the conditions of a current-carrying wire more directly:
\[ U_\text{ind} = -B \cdot v \cdot l \cdot \sin(\alpha) \]
The formula states that the magnitude of the induced voltage is proportional to the speed of the material’s motion.
The dependence of the induced voltage on speed can be clearly illustrated using the curve display in the lower right window.
The field lines of the magnetic fields can also be displayed in the animation.
Ampère’s circulation law predicts that a circular magnetic field forms around a current-carrying conductor.
\[ B = \frac{\mu_0 \cdot I}{2 \pi \cdot r} \]
Note: μ₀ is the magnetic field constant. In the profile view, the resulting magnetic field can also be displayed.
The resulting magnetic field is created by combining the dynamic magnetic field around the conductor with the static magnetic field of the horseshoe magnet.
The Lorentz force law describes the force acting on the current-carrying conductor in the magnetic field.
\[ \vec{F} = q \cdot (\vec{v} \times \vec{B}) \]
This force acts against the direction of motion of the material. Therefore, when the material is displaced, not only is a distance traveled, but force is also applied. In other words: mechanical work is done.
In technical applications, this work is performed, for example, by a turbine. The turbine can be driven by steam or— in a wind turbine — also by wind.
Note: The animation takes into account the difference between technical and physical current direction. Electrons are represented by blue spheres and indicate the physical current direction. The dot and cross symbols refer to the technical current direction.
In our everyday lives, electromagnetic induction operates almost everywhere in the background: In power plants, generators produce electricity by moving conductors through magnetic fields; bicycle dynamos convert the rotation of the wheel into electrical energy; induction cooktops heat pots because eddy currents form in the metal; transformers in chargers adjust voltages so that devices can be operated safely; wireless chargers for smartphones transfer energy through changing magnetic fields.
Overview and Download
| Title | Electromagnetic Induction 1 |
| Target Group | Teachers and Presenters |
| Platforms | Microsoft® Windows® Apple® Macintosh® (version-dependent) |
| Features | Full screen mode lossless zoom Supports large screens and projectors |
| License | Freeware |
| Download | Contact |
Contributors
C. Hein, S. Rikowski
Sources
- Authoring tool: Adobe Animate
- 3D engine for 3D model: Papervision3D 2.0
- 3D rotations: Algorithm adopted from Federico Calvo: http://blog.federicocalvo.com/2009/03/papervision-3d-sphere-globla-axis.html
- Curved field lines: Bezier3D class by Aleksandar Mancic
- Authoring tool (control elements included): Adobe Animate
Version History
| Date | Change |
| 2014-06-01 | First version |
| 2024-02-09 | New player application and minor corrections |