Lecture 4: Electrostatic Potential, Electric Energy, eV, Conservative Field, Equipotential Surfaces

author: Walter H. G. Lewin, Center for Future Civic Media, Massachusetts Institute of Technology, MIT
recorded by: Massachusetts Institute of Technology, MIT
published: Oct. 10, 2008,   recorded: February 2002,   views: 46926
released under terms of: Creative Commons Attribution Non-Commercial Share Alike (CC-BY-NC-SA)

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"We're going to talk about again some new concepts. And that's the concept of electrostatic potential electrostatic potential energy. For which we will use the symbol U and independently electric potential.

Which is very different, for which we will use the symbol V. Imagine that I have a charge Q one here and that's plus, plus charge, and here I have a charge plus Q two and they have a distant, they're a distance R apart. And that is point P. It's very clear that in order to bring these charges at this distance from each other I had to do work to bring them there because they repel each other.

It's like pushing in a spring. If you release the spring you get the energy back..."

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Reviews and comments:

Comment1 Mico Gacanovic, April 16, 2009 at 12:43 p.m.:

Thank you,

Comment2 Prof.Dr.Mico Gacanovic, September 1, 2011 at 10:29 p.m.:

Thank you

Comment3 seemad khan, October 15, 2013 at 9:34 a.m.:

Assalam-o-walikom .Is it possible to mantian electron between two arbits.

Comment4 domenico de seta, March 19, 2014 at 10:23 p.m.:

I have always had this concern at the definition of U: if I apply on q2 a force of the same magnitude and opposite direction of the Coulomb force excerted by q1 on q2 then q2 is in equilibrium and can be moved towards q1 at constant speed (no force=>no acceleration) so the two forces in equilibrium appear to make no work at all! Where's my conceptual mistake?

Comment5 Aratrik, April 9, 2014 at 12:57 p.m.:

@domenico de seta you said that you will apply a force on q2 and that means to do work.

Comment6 daniela, September 10, 2015 at 4:05 p.m.:

@domenico de seta you have to constantly apply your force on q2 to overcome electric force, and when you apply a force which causes motion in the same direction, you do work.

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