This applet displays 3-D perspective views of the magnetic field produced by a number of electric current configurations. There are options for displaying fields as vectors or field lines or for displaying the vector potential. Particle views of the fields are also available. The view can be 3-dimensional or limited to 2D planes with fixed values of X, Y, or Z. Many variables can be changed such as the external magnetic field strength, field line density, number of particles, geometric size of loops, and separation distance between loops or wires.
Type of Material:
Classroom demonstration, homework assignments, or part of a self-paced activity.
A Java-enabled browser.
Identify Major Learning Goals:
To be able to visualize the magnetic field surrounding a vast array of three-dimensional current distributions.
Target Student Population:
College students enrolled in calculus-based physics, undergraduate and graduate E & M classes along with AP High School Physics.
Prerequisite Knowledge or Skills:
Students should have been exposed to the basic laws of magnetism and the definition of magnetic field, the right-hand magnetic field rule, some calculus techniques, and the vector potential.
Evaluation and Observation
The simulation covers a good selection of current systems. Multiple views are available, including vector potential, field lines, and field vectors. An option to display the response of magnetized particles to the force generated by the field is also available. Graphics are in 3-D perspective with the viewpoint under user control.
The velocity view with particles may confuse students since it doesn't represent a physical behavior.
The uniform field example is trivial.
Potential Effectiveness as a Teaching Tool
Magnetic field diagrams are difficult to draw, and therefore visualize, for most current distributions without the help of simulations such as these because of the field's inherent 3D nature. Visualizations such as this are the only method to help gain a qualitative view of magnetic field diagrams, particularly for more complex current distributions. There are a large number of parameters that can be changed to explore the field distribution: from 3-dimensional to an X, Y, or Z slice, type of current distribution, field strength, line separation, display the field lines, field vectors, and vector potential. An external field may be introduced into each current distribution. The strength and direction of this external field can be changed. Each simulation can be stopped, reversed, or reset as well.
There is a rather large amount of information to comprehend and parameters that can be changed so learners may need guidance on the best way to approach this applet to avoid cognitive overload.
Ease of Use for Both Students and Faculty
Controls are largely intuitive, in most cases their function is fairly obvious. Detailed instructions and descriptions of the functions are also available.
Precise orientation of the applet view using the mouse can be difficult.
When first opened, the applet is in front with the homepage hiding the directions for using the applet.