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.
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.