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Question
Figure shows the field lines due to a positive point charge. Give the sign of potential energy difference of a small negative charge between the points Q and P.
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Solution
The electric potential at a point distant r due to the field created by a positive charge Q is given by
\[v = \frac{1}{4\pi \epsilon_0}\frac{q}{r}\]
Since rQ > rP, we have:
VQ < VP
∴ The potential energy difference VP − VQ is positive between Q and P.
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