Current Loop in magnetic field (How motor works!)

[Fu-Kwun Hwang]

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This simulation shows a current loop in uniform magnetic field.
The black arrows show the force due to magnetic field on the loop.
or
The magnetic field in in the +Z direction if Bz>0.
Then ,torque for the loop is calculated from definition

Because the current flow in the same counter-clockwise direction.
The force on the loop change sign during each helf cycle.
If we current reverse direction during each helf cycle, the following device can turn into a motor.
A voltage source is needed in the loop to drive the current.


P.S. The above simulation did not include the induced emf due to changing magnetic field in the loop.

You are welcomed to check out a very good animation DC motor operation principle

Registed user can get files related to this applet for offline access.
If java program did not show up, please download and install latest Java RUN TIME

[Fu-Kwun Hwang]

Registed user can get files related to this applet for offline access.
If java program did not show up, please download and install latest Java RUN TIME

Here is the real motor:

In order to make motor reach stable rotational motion. A friction force is introduced: F=-constant *b*omage;//where b is the width in y-direction
Even thought magnitude of the magnetic force is the same (black arrows),
  the torque is a function of cos(w*t)



If the process is reversed: A loop rotating in a uniform magnetic field will become electric power generator.
Please check out A loop rotating in a magnetic field (How electric power generator works!)

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[lookang]

This simulation shows a current loop in uniform magnetic field.The magnetic field in in the +Z direction if Bz>0.

1. Add vector field arrow(s) for vector Bz .

Because the current flow in the same counter-clockwise direction.

2. Add  arrow(s) line along the sides of the wires to aid visualization of I current and q current flow.
or


3. in the electron objects, can draw a negative sign -, to make it immediately association to electrons?

indeed  nice applets
can split posts into 2 separate applets for ease of discussion/collaboration etc.

thanks!

[Fu-Kwun Hwang]

I modified it according to your suggestion. However, I did not draw negative sign, because there are too many symbol shown already.
More checkboxs are added for user to decide which symbols s/he did not need! (velocity/field/force)

[lookang]

i found these applets that can be referred to for improving the Ejs applet above.

http://www.magnet.fsu.edu/education/tutorials/java/dcmotor/index.html

http://www.walter-fendt.de/ph11e/electricmotor.htm


i try to remix from your applets, i will learn a lot from remixing.

will ask again for help

[lookang]

i am done remixing Ejs Open Source DC Motor Model by Fu-Kwun Hwang and lookang
http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1266
enjoy and thanks again Prof Hwang!

http://www.phy.ntnu.edu.tw/ntnujava/index.php?action=dlattach;topic=1266.0;attach=1432;image[/img]]http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1266

[lookang]

Hi prof hwang,
found the second applet not loading like i encountered before.
load: class users.ntnu.fkh.currentloopinbmotor_pkg.currentloopinbmotorApplet.class not found.
java.lang.ClassNotFoundException: users.ntnu.fkh.currentloopinbmotor_pkg.currentloopinbmotorApplet.class
   at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source)
   at java.lang.ClassLoader.loadClass(Unknown Source)
   at java.lang.ClassLoader.loadClass(Unknown Source)
   at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Unknown Source)
   at sun.plugin2.applet.Plugin2Manager.createApplet(Unknown Source)
   at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
   at java.lang.Thread.run(Unknown Source)
Caused by: java.io.IOException: open HTTP connection failed:http://www.phy.ntnu.edu.tw/ntnujava/ejs4/users/ntnu/fkh/currentloopinbmotor_pkg/currentloopinbmotorApplet/class.class
   at sun.plugin2.applet.Applet2ClassLoader.getBytes(Unknown Source)
   at sun.plugin2.applet.Applet2ClassLoader.access$000(Unknown Source)
   at sun.plugin2.applet.Applet2ClassLoader$1.run(Unknown Source)
   at java.security.AccessController.doPrivileged(Native Method)
   ... 7 more
Exception: java.lang.ClassNotFoundException: users.ntnu.fkh.currentloopinbmotor_pkg.currentloopinbmotorApplet.class
Reading certificates from 11 http://www.phy.ntnu.edu.tw/ntnujava/ejsuser/14019/ejs_DCmotor.jar | C:\Users\160\AppData\LocalLow\Sun\Java\Deployment\cache\6.0\21\48384655-45e7ddf6.idx

[Fu-Kwun Hwang]

Thank you! It is fixed now.

[macfamous]

Sorry but I still get a little problem here .. may we have just a simple formula for this .. -*-

[Fu-Kwun Hwang]

The fomula for force and torque are provided in the previous posts.
May I know what kind of formula are you looking for?