PHGN-361 Spring
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Instructor information
Professor: Dr. Frank Kowalski
Office: Meyer 438
Office Hours:
Monday 12-2 and Tuesday 12-3.
Extra Credit Group Exam Problem Due May 2 at 10 AM
Please go to this site [1] (electric field of dreams) and play with the applet. Edit the following subsections iterating questions with answers. Generate both critical and positive comments on the questions and answers and come up with experiments to answer questions. All those participating will receive 20 extra points on exam 4 (there are 10 points per problem and about 5 problems on the exam) if the group draws insightful conclusions. Less credit will be given for less productive effort. You must log in on this wiki to participate. Please make your name apparent in the log in to receive credit.
questions
1) Energy Conservation: This reminds me of the fourth numerical assignment in Intermediate Mechanics. Do you think the total energy is conserved?
answers
1) Energy conservation: I let the applet run for a few minutes, and no, energy is definitely not conserved. With three charges, it didn't take long before they were flying around the box with an obviously higher energy than they started with. The time resolution for the simulation must not be good enough...
1) I believe Energy is conserved, setting the charge higher than the mass you can observe coulomb repulsion. Also I have not been able to observe the runaway effect stated above. I am curious however about how the collisions with the walls of the system effects this.
critical comments on the answers
positive comments on the answers
experiments to test questions
other comments
1) Energy Conservation: Something just occurred to me, which I didn't think of when I was working on the fourth numerical. Total energy could be maintained (even though there were obvious spikes in the total energy when the three masses approached one another) by normalizing the energy at each timestep, just like we do in quantum and thermal. That is to say, reduce each objects kinetic and potential energy by a factor such that their relative energies remain the same, and the total energy is constant. The only issue with this is that divvying up the energy into kinetic and potential for each particle might be a little tricky (especially because the potential depends on where each particle actually is. This would be a cool feature to go back and add to that three-body simulation, though.
Creativity Links
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Course Information
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Course videos, applets, and links
Video Lectures for March 7 through March 11 are
Here is the InkSurvey link Kowalski InkSurvey site
Homework assignment 7 has for problem 1 this link applet
and for problem 2 this link cell phone
Homework assignment 10 uses the following link [2]
Applet links:
Harmonic oscillator applet [3]
E from a moving charge [4]
Charge and field distribution on conductors and in dielectrics [5]
metal sphere inside a capacitor where the voltage across the capacitor can be varied [6]
Applet link for Faraday's Law used in the April 13 lecture [7]
Applet link for Faraday's law with a rectangular wire near a long wire [8]
Applet to calculate inductance [9]
Plinko link [10]
Lectures
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Homework Assignments:
See the syllabus for the first homework assignment.
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Homework Solutions:
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HAARP problem in assignment 12.
A part of rhetoric [11] is to manipulate the facts to sway the viewers’ opinion. You need to recognize this manipulation in the context of science and engineering (not only in politics). One example in this video is that interruptions of communications in a nuclear war are the primary objective of HAARP.
Indeed nuclear explosions generating an electromagnetic pulse (EMP) do disrupt communications by creating gamma rays whose Compton electrons spiral around the Earth’s field lines thereby producing a huge EMP (large enough to fuse 300 street lights 1300 km away). Please see the following references [12] and [13]
However, HAARP is not a nuclear weapon. Yet that doesn’t stop the authors of the video from making that false connection. Here are more reliable descriptions of HAARP along with a discussion of conspiracy theories associated with it.
Other manipulations of the facts are that the Earth’s rotation rate will be dramatically affected. It is easy to calculate the energy required to do this and compare it with the electromagnetic energy that can be generated.
Just like in the applets you need to think critically about the information you find. Here are some resources
-the effects of HAARP [14]
-HAARP on wikipedia [15]
Exams with solutions and Rubrics
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Old Exams with solutions and Rubrics
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Problem solving strategies and sample problems:
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Volume and surface integrals in cylindrical coords [16]
Line integrals
Delta functions
