NTNUJAVA Virtual Physics Laboratory
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"That their main business was not put into the mind knowledge which was not there before, but to turn the mind's eye towards light so that it might see for itself." ...Plato's advice to educators(429-347BC)
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Author Topic: Electron in magnetic field  (Read 52660 times)
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Fu-Kwun Hwang
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on: May 16, 2005, 03:09:01 pm »

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It is assumed there are uniform magnetic field in the simulation region except white background area (there is no magnetic field).
An electron enter magnetic field is not trapped in the magnetic field. It will come out the region eventually.

You can change charge/ mass /magnetic field and the width of the white region with sliders. Enjoy it!



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d211275
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Reply #1 on: May 09, 2007, 09:51:15 am » posted from:Suzhou,Jiangsu,China

Thanks alot.It's very useful for me.
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Fu-Kwun Hwang
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Reply #2 on: May 18, 2007, 11:51:40 pm »

You are welcomed!
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Gizmo0105
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Reply #3 on: September 26, 2007, 04:39:22 pm » posted from:ABERDEEN,SCOTLAND,UNITED KINGDOM

Hi, thanks a lot for the simulation its very helpful.

Im currently doing an investigation for school on electrons in magentic and electrostatic fields. However I cannot perform the most common investigation (Charge to mass ratio) as this is already in the course.
Any suggestions would be greatly appreciated
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Fu-Kwun Hwang
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Reply #4 on: September 27, 2007, 12:51:09 am »

For electron with charge q move in E and B field.
The force will be q (E+vXB)
If the acceleration is a, and mass is m, then

ma= q (E+vXB) ;
so a=(q/m) (E+vXB)

If you can measure acceleration(in any way). You will know the q/m ratio.
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Ganeshchandra
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Reply #5 on: October 29, 2007, 06:33:22 pm »

thanks
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basit_fastian
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Reply #6 on: November 16, 2007, 11:41:47 am »

hi
thanks for this beautiful site and knowledge of physics keeping on the java aplet and this aplet give me a lot of knowledge to me about eletron in magnetic field.
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Alfcon
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Reply #7 on: September 11, 2009, 06:51:26 am » posted from:Melbourne,Victoria,Australia

I am new to all this and have just started to teach my self some of the basic aspects of Electrons and magnetic fields.  I have looked at your java program in the Topic: Electron in magnetic field, and I have a few questions.

Q = charge
m = mass
d = Magnetic field
b = ?

What does b represent ?
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Fu-Kwun Hwang
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Reply #8 on: September 11, 2009, 08:32:26 am » posted from:Taipei,T\'ai-pei,Taiwan

B stands for magnetic field : there is a uniform magnetic field in most of the simulation region except region with white background.
d: is the width of the white back ground region where there is no magnetic field (B=0).

Try to change slider value and watch what is changed in the simulation.
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Alfcon
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Reply #9 on: September 11, 2009, 10:33:49 am » posted from:Melbourne,Victoria,Australia

ok got it now, one more question. 

If b is the magnetic field and i can be set from 1 to 10.

Is b set to 1 =  1 Tesla, b set to 10 = 10 Tesla?

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Fu-Kwun Hwang
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Reply #10 on: September 11, 2009, 02:40:41 pm » posted from:Taipei,T\'ai-pei,Taiwan

This is a good question. Because you might reach a wrong interpreatation if you was not careful when chose unit for the ststem.

\vec{F}=q \vec{v}\times \vec{B} is used to calculate the motion in the simulation.
For a simulation, the same length in the simulation can be 1cm or 1m or 1km.
It depends on how you interprete the system.

In the above system, you can select the unit of B as Tesla, then the unit in space (x,y coordinate) will be meter, charge will be Coulomb. Unit for velocity will be m/s.

If you want to interprete it as a real electron:
qe=1.6 10-19 C, me=9.1 10-31kg.
m_e/q_e=5.69 10-12 kg/C,

If you want to interprete B as Tesla, then the unit of 1 second in the simulation represent 5.69 10-12s in real case. It means that the electron will move very fast. However, it can not be faster then speed of light c=3 108m/s (less than 0.01c will be fine to ignore relativistic effect), so the unit of length can not be meter(m). However, \mum (10-6m) can be used.

If the unit of B is selected as gauss (1 gauss=10-4 Tesla), then unit of length can be selected as mm (10-3m).
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"That their main business was not put into the mind knowledge which was not there before, but to turn the mind's eye towards light so that it might see for itself." ...Plato's advice to educators(429-347BC)
 
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