InterviewSolution
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InterviewSolution
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A charge `q` is placed at the some distance along the axis of a uniformly charged disc of surface cahrge density `sigma`. The flux due to the charge `q` through the disc is `phi`. The electric force on charge `q` exerted by the disc isA. `sigma phi`B. `(sigma phi)/(4pi)`C. `(sigma phi)/(2pi)`D. `(sigma phi)/(3 pi)` |
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Answer» Correct Answer - a We know that if a point charge subtends a half-angle `alpha` on the circular cross-section of a disc, then flux passing through the disc is : `phi=(q)/(2 epsilon_(0))(1- cos alpha)` Also, if a point charge `q` lies on the axis of a charged disc of charge density `sigma` and subtends a half-anlge `alpha`, then it experiences a force `F= (q sigma)/(2 epsilon_(0))(1-cos alpha)= sigma phi` |
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