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A couple of concepts I would like to understand.

by Lifprasir
Tags: concepts, couple
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Lifprasir
#1
Feb19-12, 09:16 PM
P: 13
They say that electrons move from the higher potential to the lower potential. For example, in this situation.



Q1 and Q2 are negative charges and Q3 is positive. But, the equipotential is lower on the Q1 and Q2, so by definition of potential difference, the electron would go from the positive to the negative. But isn't there another concept that says opposites attract? so shouldn't the electron go to the positive charge? I don't quite understand what is happening here.
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glenn21
#2
Feb19-12, 10:15 PM
P: 19
Yes the electron would want to go towards the positive charge, the force due to opposite charges is attractive, but there is also a repulsive force due to the negative charge. The direction Q1 will travel for example depends on the relative distances q2 and q3 are away from it and also the charges they have.

I think I know where your coming from about high to low potential, but try thinking in terms of magnitudes, an example is in a circuit with a battery and a resistor. In magnitude the electrons have a high voltage at the start and a low voltage at the end. With the setup you have shown for example, say the proton has a high postive charge, then thinking in a magnitude type manner the electron will have zero joules of energy when it reaches the proton. It will technically have +5J or so of energy, but it won't use that energy to move around and so it is useful to think of it as being 0J to move around with.


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