Ejs Open Source Magnet Falling Through Ring Model Java Applet

Ejs Open Source Magnet Falling Through Ring Model Java Applet remix by lookang
 http://weelookang.blogspot.com/2011/01/ejs-open-source-magnet-falling-through.html   author: Francisco Esquembre and remixed by lookang http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=2066.0 author:Francisco Esquembre and lookang  https://dl.dropboxusercontent.com/u/44365627/lookangEJSS/export/ejs_model_MagnetFallingThroughRingwee.jar https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejs_users_sgeducation_lookang_MagnetFallingThroughRingwee.jar
screenshot of applet

this is a remixed of the original model http://www.compadre.org/osp/items/detail.cfm?ID=10327
by Francisco Esquembre

The Magnet Falling Through Ring model shows the dynamics and the induced current (voltage) when a magnet falls through a conducting ring.

The current in the ring is computed by electromagnetic induction using to Faraday's law and the induced emf is proportional to the negative of the rate of change of magnetic flux. The direction of the induced current is determined by Lenz's law, the induced current produces magnetic field which tends to oppose the change in magnetic flux that induces such currents.

Magnet falling through a ring
When a magnet falls through a ring, current is induced in the ring. This phenomenon is called electromagnetic induction.

According to Faraday’s law, the induced emf is proportional to the negative of the rate of change of magnetic flux Φ. The direction of the induced current is determined by Lenz’s law, the induced current produces magnetic field which tends to oppose the change in magnetic flux that induces such currents.

The voltage induced when a magnet is falling through a ring is simulated in this experiment, where we model the magnet as a magnetic 'dipole'. The current is visualized by very big 'electrons' that move according to the strength of the current.

Please, complete this set of Minds-On questions:
Explain the shape (positive and negative peaks) of the recorded signal.
Why the peaks are not symmetric?
At which moment was the magnetic flux changing most quickly?
What was the total change of magnetic flux during the first half of the magnet’s fall - while it was moving in to the coil?
What was the total change of magnetic flux during the second half of the magnet’s fall - while it was moving out of the coil?
How could you change the simulation to increase the magnitude of the sign?
This simulation was created as part of the MOSEM2 project.

changes

1 redesign the layout to fit my usual format
2 added text on green electrons for eye-balling purposes
3 set initial r = 0.1 instead of the usual 0.03, the electrons are moving too fast for r=0.03
4 add magnetZs as slider for the initial magnetZ, modified the codes slightly magnetZ = freeFallZ = magnetZs/4 ; // insead of the older code = maximum/4
5 bug the text didn't compile in Java3D so i did it on simple3D

to do list
to add the model for a cylinder ?, currently it is only for a ring of very small Z thickness
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