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A charged sphere of diameter `4` cm has a charge density of `10^(-4) "coulmb"//cm^(2)`. The work done in joule when a charge of 40 nano-columbs is moved from infinity to a point which is at a distance of 2 cm from the surface of the sphere is-A. `14.4 pi`B. `28.8 pi`C. `144 pi`D. `288 pi` |
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Answer» Correct Answer - A `w= qDeltaV` `sqrt(AB) = sqrt(2) = 1.4` and error in `sqrt(AB)` Let `Z = sqrt(AB)` `(DeltaZ)/(Z) = (1)/(2) (DeltaA)/(A) + 1/2 (DeltaB)/(B)` `(DeltaZ)/(1.4) = 1/2 ((0.2)/(1)) + 1/2 ((0.2)/(2))` `(DeltaZ)/(1.4) = 0.1+ 0.05` `Delta Z = (0.15)(1.4) = 0.21` `Z = (1.4+0.2) m` |
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