Ejs Open Source Bar Magnetic Field Lines Model Java Applet

[lookang]

Ejs Open Source Bar Magnetic Field Lines Model Java Applet

made possible thanks to
Michael Galis http://www.compadre.org/osp/bulletinboard/TDetails.cfm?ViewType=2&TID=2226&CID=51612&#PID51613

and Wolfgang Christian http://www.compadre.org/osp/items/detail.cfm?ID=12361

Embed a running copy of this simulation
<applet code='users.sgeducation.lookang.fieldlines3Dwee01_pkg.fieldlines3Dwee01Applet.class' archive='http://www.phy.ntnu.edu.tw/ntnujava/ejsuser/14019/ejs_fieldlines3Dwee01.jar' name='fieldlines3Dwee019515' id='fieldlines3Dwee019515' width='300' height='300' mayscript=true><param name='draggable' value='true'></applet>
Embed a running copy link(show simulation in a popuped window)
<a href='http://www.phy.ntnu.edu.tw/ntnujava/msg.php?smfejs=9515' target='smfejs'>Run simulation</a>

Full screen applet or Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop. This work is licensed under a Creative Commons Attribution 2.5 Taiwan License

• Please feel free to post your ideas about how to use the simulation for better teaching and learning.
• Post questions to be asked to help students to think, to explore.
• Upload worksheets as attached files to share with more users.

Let's work together. We can help more users understand physics conceptually and enjoy the fun of learning physics!

work in progress.

My own naive idea is to use analyticCurve3D but i haven't seen any example on a family of analyticCurve3D, so each is drawn as a single analyticCurve3D.

the match is close but not very accurate
http://en.wikipedia.org/wiki/Ellipse
An ellipse in general position can be expressed parametrically as the path of a point (X(t),Y(t)), where
Minimum = 0
Maximum = 2*Math.PI
Variable = "theta"
X() = "1.4+1.4*Math.cos(theta)*Math.cos(0)-1.4*Math.sin(theta)*Math.sin(0)"
z()= "0+0.5*Math.sin(theta)*Math.sin(0)-1*Math.sin(theta)*Math.cos(0)"

[lookang]

still cannot make the sim run without run-time errors.
attached is the new sim with 2 sets of field lines

[Fu-Kwun Hwang]

You have learned how to draw electric field line from http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=539.0

You can use the same method to draw magnetic field line.

I tried to open ejs model from your jar file. However, I was not able to understand what you were doing in the model (evolution page: lambdax, lambday, lambdaz???)

[lookang]

You have learned how to draw electric field line from http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=539.0

You can use the same method to draw magnetic field line.

I tried to open ejs model from your jar file. However, I was not able to understand what you were doing in the model (evolution page: lambdax, lambday, lambdaz???)

it is very difficult for me to implement it is 3D as i only have very limited knowledge, the codes you invented http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=539.0 are too advanced for me redesign in 3D.
i can remix
 

I tried to open ejs model from your jar file. However, I was not able to understand what you were doing in the model (evolution page: lambdax, lambday, lambdaz???)

according to prof mike gallis http://www.compadre.org/osp/bulletinboard/TDetails.cfm?ViewType=2&TID=2226&CID=51612&#PID51613

For a parameterized path in space λ(t) tangent in space which "follows" a field E(r) the rate of change of the path (the "velocity" of the trajectory) is in the direction of the field. The first try:

dλ(t)/dt = E(λ(t))

this method works in principle, but in numerical approaches, the computed path λ(t) will have large step sizes where the field is strong, which is probably undesireable. I prefer:

dλ(t)/dt = E(λ(t))/|E(λ(t))|

which gives the path a "constant velocity".



For a dipole field (from Jackson):

E(r) = (3n(p⋅n)-p)/|r-r0|3
r = field point
r0 = location of dipole
p = dipole moment
n = normal vector pointing from source to field point = (r-r0)/|r-r0|

For the example coded here, the source is at the origin (r0 = 0) and the dipole is oriented along the z axis. With the coordinates of the field point given as x,y,z (and r= x2+y2+z2)1/2 ) the field components are
Ex=3xzp/r5
Ey=3yzp/r5
Ez=3z2p/r5 -p/r3

[Fu-Kwun Hwang]

OK. I understand what you are trying to do now. I will try to check out your model and see what I can do to help!
 

[Fu-Kwun Hwang]

The following is the version modified from your EJS model.

Embed a running copy of this simulation
<applet code='users.ntnu.fkh.fieldlines3Dwee03a3_pkg.fieldlines3Dwee03a3Applet.class' archive='http://www.phy.ntnu.edu.tw/ntnujava/ejsuser/2/ejs_fieldlines3Dwee03a3.jar' name='fieldlines3Dwee03a39731' id='fieldlines3Dwee03a39731' width='562' height='460' mayscript=true><param name='draggable' value='true'></applet>
Embed a running copy link(show simulation in a popuped window)
<a href='http://www.phy.ntnu.edu.tw/ntnujava/msg.php?smfejs=9731' target='smfejs'>Run simulation</a>

Full screen applet or Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop. This work is licensed under a Creative Commons Attribution 2.5 Taiwan License

• Please feel free to post your ideas about how to use the simulation for better teaching and learning.
• Post questions to be asked to help students to think, to explore.
• Upload worksheets as attached files to share with more users.

Let's work together. We can help more users understand physics conceptually and enjoy the fun of learning physics!

[lookang]

The following is the version modified from your EJS model.
ejsuser/2/ejs_fieldlines3Dwee03a3.jar not found

hi prof!
need to upload again?

[Fu-Kwun Hwang]

Sorry! I should have checked it. It is OK now.