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Author Topic: Ejs Open Source Long Magnet Falling Through Ring Model Java Applet  (Read 15456 times)
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lookang
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on: February 04, 2012, 03:41:10 pm » posted from:Rancho Cucamonga,California,United States

Ejs Open Source Long Magnet Falling Through Ring Model Java Applet by lookang based on a original model by http://www.compadre.org/osp/items/detail.cfm?ID=10327 Magnet Falling Through Ring Model written by Francisco Esquembre.
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http://iwant2study.org/ospsg/index.php/interactive-resources/physics/05-electricity-and-magnetism/09-electromagnetic-induction/349-ejs-falling-magnet-3d-model


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adapted to fit the new model of a long magnet made by an array of magnetic dipoles instead of the original model of a single magnet dipole.

Long Magnet falling through a ring
When a long 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 vertical set of magnetic 'dipoles'. 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.

« Last Edit: January 26, 2016, 09:37:44 am by lookang » Logged
lookang
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Reply #1 on: February 04, 2012, 03:45:14 pm » posted from:Rancho Cucamonga,California,United States

changes

add array
made the magnet as 10 individual magnets instead of the original single magnetic dipole
made variable magnetZ as slider that controls the model, it was not easy, cant recall what i did now.
magnetLength as slider
position 10 magnets across the magnetLength equally spaced
variable coilZ as slider that controls the model
add current and individual current to debug a problem with original codes that cause a unusual spike in the tension = voltage.
redo the voltage and seems to be okay now

time to sleep. 1 am
got workshop later Smiley at 8 am

more changes
made the ball freeFallZ = magnetZ[n/2-1]; // match centre of magnet
made n = 30 for smoother graph


found this great activity by Pasco
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCMQFjAA&url=http%3A%2F%2Fwww.lhup.edu%2Fgp%2Fphysics%2FLabs%2F131_s11_PASCO_Induction_v2.docx&ei=4TotT_qKK8yJtwfXp_nfDw&usg=AFQjCNG2rafzaOKWiQpeNUThUACMxu2BNg&sig2=DvZDJYqVVzH8-xkql9l5rg


* emifalling.png (26.12 KB, 705x541 - viewed 381 times.)

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« Last Edit: February 04, 2012, 09:09:57 pm by lookang » Logged
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Reply #2 on: February 08, 2012, 12:43:53 am » posted from:Rancho Cucamonga,California,United States

discussion with teacher

> May I know if you could fix the issue with the voltage graph. It seems that the voltage graph does not invert when I change the polarity of the magnet.
>
Let me check, thanks for the bug reporting, it is fixed now

> Also, just to inform you that there is a double shadow curve on the current panel? Is it normal?
>
It is the sum of the individual magnets Smiley
i also juts added check-boxes to activate the sum and the individual currents.
By the way, did u know of any other applet in the Internet that shows the same physics? I suspect this is a world first for long magnet!!
It is awesome Wink


add the correct laying of the north and south pole
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Reply #3 on: February 08, 2012, 06:43:45 am » posted from:Rancho Cucamonga,California,United States

more discussion with teacher

   I am very impressed with your email response. very fast.
  

u should be more impressed by the computer model that i will release soon, solenoid (version i will release later) instead of a single ring (original from OSP) and a bar magnet (version u saw) instead of a single magnetic dipole.(original from OSP)
i would dare say no vendor can create what you want in 3 weeks.



   By the way, could you help me to understand what do you mean by "sum of individual magnets"? There is only one magnet, isn't? What are those small black graphs on current panel?
  

in computer modeling, magnetism is manifested by creating single point magnetic dipole, like point charges, but here as magnetic charges.
to create a model of a bar magnet, what i did was to create a series of magnetic dipole inside the bar to simulate as a single bar magnet.
so to answer the question, the black lines are individual contribution of the magnetic dipoles with the ring based on each magnetic dipole distance away from the ring.
currently there are 30 of these magnetic dipoles Smiley
the resultant is pretty smooth and realistically physics based, not animation cartoon drawing so to speak.

 

   I realise that you are on some conference, maybe you can email when you are free. Thanks for your support.
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Reply #4 on: April 17, 2014, 03:38:05 pm » posted from:Atlanta,Georgia,United States

Since they use Long magnet, the magnetic field would be very high and we can produce a large output in a short period of time. This can result in good productivity with less effort and in a cheap budget. Good work!







JANE
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Reply #5 on: January 26, 2016, 09:38:07 am » posted from:SINGAPORE,SINGAPORE,SINGAPORE

new host
http://iwant2study.org/ospsg/index.php/interactive-resources/physics/05-electricity-and-magnetism/09-electromagnetic-induction/349-ejs-falling-magnet-3d-model
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