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A very large (infinite) plane sheet carries uniform positive surface charge density sigma. Two points P1 and P2 lie at perpendicular distances l and 2l from the sheet. What are the magnitudes of the electric fields E1 (at P1) and E2 (at P2)?
- E1 = sigma/epsilon0, E2 = sigma/(2*epsilon0)
- E1 = 2*sigma/epsilon0, E2 = sigma/epsilon0
- E1 = E2 = sigma/(2*epsilon0)
- E1 = E2 = sigma/epsilon0
Correct answer: E1 = E2 = sigma/(2*epsilon0)
Solution
An infinite plane sheet of charge produces a uniform field of magnitude sigma/(2*epsilon0) on each side, independent of distance from the sheet. Therefore the field is the same at P1 and P2: E1 = E2 = sigma/(2*epsilon0).
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