• If you are citizen of an European Union member nation, you may not use this service unless you are at least 16 years old.

  • Social distancing? Try a better way to work remotely on your online files. Dokkio, a new product from PBworks, can help your team find, organize, and collaborate on your Drive, Gmail, Dropbox, Box, and Slack files. Sign up for free.


Potential energy of charges

Page history last edited by Joe Redish 3 years, 6 months ago



In the figure at the right are shown two settings of positive and negative charges (labeled I and II). Setting I has two positive charges; setting II has one negative charge and one positive charge. Each of the charges has the same magnitude, Q

(i) If one large grid box in the diagram has a magnitude d, using E0 = kcQ2/d, express the total electric potential energy of each arrangement as 

E = nE0

where n is some dimensionless number. 


(ii) In each setting, two positions are labeled. If a positive test charge of magnitude is added at each position (there is one test charge in the system at any time), rank the magnitude of the extra potential energy the charge would add to the system at each of the four places, indicating if any are 0. (Like this E=F>G>H=0).


Explain your reasoning.


(iii) There are two situations (I and II), two possibilities for the test charge (positive and negative), and four possible positions (A, B, C, and D). This gives 2 x 2 x 4 = 16 possibilities. Which has the largest electric PE? The largest magnitude of PE? The smallest PE?


Explain your reasoning.


Joe Redish 11/20/16 


Comments (0)

You don't have permission to comment on this page.