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14A point charge 9 is kept at the centre of a fixed semicircular thread having a uniform charge per un sengthe radius of the semicircular thread being R. The force required to keep the charge stationary is |
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Answer» Answer: Force required is 2kqa/r Explanation: Point kept at centre = q Radius = R Charge at the segment rdθ =ardθ The horizontal component of force will be cancelled out as the ring will be symmetric about y axis Vertical force =Fcosθ =kqardθ/r2Cosθ =kqa/r cosθ dθ Thus, total force = limit 0 to 90, 2∫ kqa/r cosθ dθ = limit 0 to 90, 2kqa/r∫ cosθ dθ = 2kqa/r |
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