Dante,
I am still questioning about the problem that Prof gave on wednesday, the topomap.
The question was how much work would it take to move +1.o micro coulomb of charge from A to B (where the potential of B is higher than that of A by 4V).
I remember you explaining it and the sign is negative?
Also read p.668 on the textbook, it says "positive charges accelerate in the direction of decreasing electric potential".
Does that mean that if it goes in the direction of increasing V, it decelerates? then the work is negative?
When work is needed, is the sign negative? or positive?
Signs always confuse me. I have problem with the sign of electric potential and potential energy as well.
Please help.
thanks
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So if you want to use the method I showed you which was W = -deltaU you have to know the sign of the charge. Since V = U/q, U = qV however the q in that equation is NOT the absolute value. Therefore:
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W = -qV
deltaV=4.0V-0.0V = 4.0V
but depending on the sign of the charge that is doing the traveling the sign of the work could be positive or negative. I am not sure how he determines the negative and positive on those equipotential surfaces so I will email him and see what he says.
Allright, thanks
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