SUBJECT: The TeachSpin™ Applet
NOTE: You must be connected to the Internet the first time you view this simulation, at which point the codebase for all the simulations will be downloaded to your computer. This process make take a few minutes, as the codebase is roughly 9MB in size. Subsequent viewings of the applets will run from your local copy.
DESCRIPTION: This applet is a simulation of the TeachSpin experiment, in which a magnet is suspended by a spring between two current-carrying coils (in Helmholtz configuration). As a current is run through the coils, the magnet, whose orientation has been fixed such that its north pole points upwards, feels a force dependent on the direction in which the current is flowing in each coil. The two basic configurations are one in which the current in one coil flows opposite the direction of the current in the other coil, and one in which the currents in both coils flow in the same direction. In the first case, the magnet will feel a repulsive force from one coil and an attractive force from the other, causing it to be displaced vertically. In the second case, the magnet feels a repulsion or attraction from both coils simultaneously, which cancel each other out, leaving the magnet undisplaced between the coils.
In the applet, you can vary several parameters, including the relative direction of the currents and their magnitudes. In addition to varying the current manually, you can turn on a signal generator that will produce a sinusoidal current that causes the magnet to oscillate (or not) at the given frequency and amplitude.
VISUALIZATION: Start Simulation (you must have Java™ J2SE v1.4+ JRE installed. Mac OS X users need the Java3D update.)