Screen shots of the dipole and test charge. EJSS on the LEFT and EJS on the right.

Dipole Trajectory Wrong Model

The EJSS Dipole Trajectory Wrong model shows the electric field generated by a dipole. Drag and drop the 2 dipole charges to any position to change the separation between the charges. A test charge moves in the dipole field and shows its velocity vector, but its trajectory is incorrect. Users can examine and correct the model if Ejs is installed.

Exercises:

Run the simulation and observe the dipole field due to fixed charges (red and blue) . Also note the trajectory of the test charge.* You can move the test charge anywhere on the screen (except on top of one of the stationary charges). You can also change the separation by dragging on the charges, between the two fixed charges.
What is wrong with this simulation? What is your evidence? Hint: Pause the simulation at several points and look at the velocity vector. Compare it with the Electric field. Should the velocity point in the same direction as the field? Why or why not?
If you have EJSS installed, now that you have determined what is wrong with the model, correct it. You will need to go to Model->Evolution to make the changes. Describe how you changed it and how you verified your work.

*Recall that a test charge is defined to feel the effects of an external electric field, but not change the field itself (therefore, there are no field vectors around it).

References:

Giancoli, Physics for Scientists and Engineers, 4th edition, Chapter 21 (2008).

Credits:

The Dipole Trajectory Wrong Model was created by Anne J Cox, Wolfgang Christian, and Francisco Esquembre and JavaScript version by lookang using the Easy JavaScript Simulations (EJSS) authoring and modeling tool. Exercises written by Anne J Cox, updated by Darren Tan and lookang.

You can examine and modify a compiled EJSS Model.

Using the EJSS authoring toolkit installed here, Select "A EJSS digital Library", in Library select "JS EJS model in Singapore", double click folder "05electricitynmagnetism_11efield", and double click filename "DipoleTrajectoryWrong" and click button "Download". Save the model source code inside your EJSS defined workspace/source/

; You must, of course, have EJSS installed on your computer.

Information about EJSS is available at: <http://www.um.es/fem/Ejs/> and in the OSP ComPADRE collection <http://www.compadre.org/OSP/>.