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Easy Java Simulations (2001- ) => electromagnetism => Topic started by: ahmedelshfie on June 10, 2010, 12:35:30 am



Title: Charge in a uniform magnetic field in 3D
Post by: ahmedelshfie on June 10, 2010, 12:35:30 am
This following applet is Charge in a uniform magnetic field in 3D
Created by prof Hwang Modified by Ahmed
Original project Charge in a uniform magnetic field in 3D (http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1450msg5484;topicseen#msg5484)

$\vec{F}=q\vec{v}\times\vec{B}$.
The following show a charged particle trapped bwtween two uniform field.
You can use sliders to change the width and the separation between two sets of magnet.
The magnetic field is assumed to be uniform Bz\hat{z} inside the magnet region. and the field is zero when outside the boundary.

You can change the location and velocity of the charged particle with mouse drag and drop or with sliders.


Title: Re: Charge in a uniform magnetic field in 3D
Post by: lookang on October 04, 2010, 12:17:40 pm
http://link.aip.org/link/?AJP/65/726/1
46% of students surveyed got this question wrong, that means false.
A constant magnetic field never changes the speed magnitude of velocity… of a charged particle which moves in it. (Bagno & Eylon, 1997)

the analysis are:
a. Recitation of formula: field applies force, and force causes acceleration according to Newton’s second law of motion 40% of 46% who got it wrong
b. Blind substitution into formula 37
c. No reason 23



Using this applet, you can see the velocity does not change.
A constant magnetic field never changes the speed magnitude of velocity… of a charged particle which moves in it.
the answer is (true)

Bagno, E., & Eylon, B.-S. (1997). From problem solving to a knowledge structure: An example from the domain of electromagnetism. American Journal of Physics, 65(8), 726-736. doi: 10.1119/1.18642


Title: Re: Charge in a uniform magnetic field in 3D
Post by: lookang on October 04, 2010, 12:23:30 pm
hmmmm, i think i need to customize it for exploring and visualization of


The velocity of a charged particle moving in a magnetic field is always perpendicular to the direction of the field.
37% think it is true, but the answer is false. it could be a supposition of uniform velocity and circular motion, thus there is an angle =! 90o between v and B, much like a helix path

a. Recitation of formula: v, B and F are always perpendicular according to left hand or right screw law 81
b. No reason 19