### Author Topic: Ejs Open Source Lorentz force on a current carrying wire java applet  (Read 24313 times)

#### lookang

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##### Ejs Open Source Lorentz force on a current carrying wire java applet
« on: February 01, 2010, 11:35:51 am »
Ejs Open Source Lorentz force on a current carrying wire java applet by lookang customized from a simulation from http://www.um.es/fem/EjsWiki/Main/ExamplesLorentzForce by Francisco Esquembre.
Shout out thanks to the Francisco Esquembre, Fu-Kwun Hwang, Christian Wolfgang of open source physics community.
i was browsing through Ejs library of open source codes and found Lorentz Force to be a suitable applet for customization.
Lorentz force on a wire
This program simulates the force exerted by a magnetic field between two magnets on an electrical current trough a wire.
The wire is kept in equilibrium in the absence of gravity, suspended on a spring and will oscillate when the battery (which is connected to the ends of the wire) is turned on and off, the angle of the wire with respect to the magnetic field is changed, or the poles of the magnets are switched.
reference: http://www.walter-fendt.de/ph14e/lorentzforce.htm

Full screen applet or Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
• 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!

« Last Edit: December 20, 2010, 12:24:25 pm by lookang »

#### lookang

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##### Re: Lorentz force on a wire by Francisco (Paco) Esquembre
« Reply #1 on: February 18, 2010, 10:45:44 am »
changes:

1 redesign the evol page to ddz/dt = vz & dvz/dt = -k*dz/m -b*vz/m + force()/m
2 redesign the way the B field is drawn to go to the edge of the magnets to reflect the "zone" which the magnetic force is experienced in the G field.
3 add text S and N
4 add B field to work with the older codes
8 add alpha, which i recoded to be the angle of I and B instead of the older I with x axis for ease of relating to the formula F = I.B.L.sin?
9 made force() work when in the B field
11 remove some other codes that must be removed to free up the simulation
12 add FBI arrows and text to be drawn to ease symbolic learning
20dec 2010
16 added particles visualization of current and electrons
17 added system view inspired by http://www.walter-fendt.de/ph14e/lorentzforce.htm using codes from Fu-Kwun Hwang from http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1266.0

« Last Edit: December 20, 2010, 10:32:29 am by lookang »

#### lookang

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##### Re: Ejs Open Source Lorentz force on a current carrying wire java applet
« Reply #2 on: November 15, 2010, 05:43:45 pm »
new remix!

For 5058 PHYSICS (WITH SPA) ORDINARY LEVEL 2011
21. Electromagnetism
Content
• Magnetic effect of a current
• Applications of the magnetic effect of a current
• Force on a current-carrying conductor
• The d.c. motor
Learning Outcomes:
Candidates should be able to:
(c) describe experiments to show the force on a current-carrying conductor, and on a beam of
charged particles, in a magnetic field, including the effect of reversing
(i) the current
(ii) the direction of the field

same for 5116 SCIENCE (PHYSICS, CHEMISTRY) & 5117 SCIENCE (PHYSICS, BIOLOGY)

#### lookang

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##### Re: Ejs Open Source Lorentz force on a current carrying wire java applet
« Reply #3 on: December 13, 2010, 01:24:54 pm »
other resources
http://www.walter-fendt.de/ph14e/lorentzforce.htm by Walter Fendt most popular applet mirror by many
* like the system view of the wires and the battery to give context.
« Last Edit: December 20, 2010, 10:51:34 am by lookang »

#### lookang

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##### Re: Ejs Open Source Lorentz force on a current carrying wire java applet
« Reply #4 on: December 13, 2010, 04:28:11 pm »
exercise by lookang

Introduction www.bk.psu.edu/faculty/gamberg/mag_lab.doc
A current-carrying wire in a magnetic field experiences a force. The magnitude and direction of this force F, depend on four variables:
the magnitude and direction of the current (I),
the strength and direction of the magnetic field (B)
the length of the wire expose to magnetic field is (L)
the angle between the current I and field B is (?)
Advanced: The force can be described mathematically by the vector cross-product:
O level: Fleming’s Left Hand Rule predicts the using the left hand, F (thumb) B (index finger) I (middle finger)
image from National High Magnetic Field Laboratory http://www.magnet.fsu.edu/education/tutorials/java/handrules/index.html

Advanced: F = I ^ B. L where ^ is the cross product
O level and A level: F = I . B. L.sin ? where ? is the angle between I and B

where
Force F is in newtons N
current I is in amperes A
length L in meters m
magnetic field B in teslas T

The direction of the force F is perpendicular to both the current I and the magnetic field B, and is predicted by the Advanced: right-hand cross-product rule.
O level and A level: Fleming’s Left Hand Rule

Engage:
a real live demo is the best.!!

Engage 1: Would you believe that a wire can jump up even though it is not alive?
Engage 2: have you thought about how a direct current can cause a rotating motion which can be used to drive some simple toys (e.g Tamiya cars) ?
http://www.tamiya.com/english/products/42183trf502x/top.jpg

Explore
1. Explore the simulation, this simulation is designed with a wire supported by a spring in a system of magnetic fields in y direction.
2 The play button runs the simulation, click it again to pause and the reset button brings the simulation back to its original state.
3 by default values B, I, L, play the simulation. Notice that the wire is in its motionless in its previous state of motion. What is the physics principle simulatted here.
hint: newton's 1st law
4 reset the simulation.
5 using the default values(L = 1 m, ? = 90 deg), adjust the value of By =1 and Ix =1 play the simulation. what did you observe? explain the motion in terms of the influences of magnetic field (assume gravitational effect can be neglected, in this computer model gravity is not model)
6 explore the slider z. what do this slider control?
7 explore the slider vz. what does this slider control?
8 by leaving the cursor on the slider, tips will appear to give a description of the slider. you can try it the following sliders such as the drag coefficient b.
9 there are some value of time of simulation t and the checkbox graph for height vs time.
10 vary the simulation and get a sense of what it does.

11 reset the simulation
Mechanics
12 using the default values (By =0, Ix=0) set z = -0.6, vz=0, b=0). Observe the motion of the wire in the absence of magnetic field. Predict what you will see. Describe the motion of the wire. Explain why this it is so?
hint: select the checkbox to view the scientific graph of height vs t.
13 using the default values (By =0, Ix=0) set z = -0.6, vz=0, b=1). Observe the motion of the wire in the absence of magnetic field. Predict what you will see. Describe the motion of the wire. Explain why this it is so?
hint: select the checkbox to view the scientific graph of height vs t.
14 using the default values (By =0, Ix=0) set z = -0.6, vz=1, b=0). Observe the motion of the wire in the absence of magnetic field. Predict what you will see. Describe the motion of the wire. Explain why this it is so?
hint: select the checkbox to view the scientific graph of height vs t.
15 using the default values (By =0, Ix=0) set z = -0.6, vz=1, b=1). Observe the motion of the wire in the absence of magnetic field. Predict what you will see. Describe the motion of the wire. Explain why this it is so?
hint: select the checkbox to view the scientific graph of height vs t.
16 conduct more scientific inquiry into the simulation if need before the next part of the question.
Elaborate
17 explain the effects of b, the model used is drag force = b.v.

18 reset the simulation
Magnetic Force
Evaluate:
19 A scientist hypothesis "O level and A level: F = I . B. L. where ? =90 deg" play the simulation for different initial condition and design an experiment with tables of values to record systematically, determine whether the hypothesis is accurate.

20 what is the impact of the ? != 90 deg ?
21 Suggest a better hypothesis
22 This computer model does not build in gravity, suggest with reason(s) why you agree or disagree with this statement. You can examine and modify this compiled EJS model if you run the model (double click on the model's jar file), right-click within a plot, and select "Open EJS Model" from the pop-up menu. You must, of course, have EJS installed on your computer. Information about EJS is available at: and in the OSP comPADRE collection

Have Fun!
« Last Edit: December 20, 2010, 01:27:08 pm by lookang »