InterviewSolution
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InterviewSolution
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Two concentric spheres kept in air have radii R and r. They have similar charge and equal surface charge density `sigma`. The electrical potential at their common centre is (where, `epsi_(0) =` permittivity of free space)A. `(sigma (R + r))/(epsi_(0))`B. `(sigma (R - r))/(epsi_(0))`C. `(sigma (R + r))/( 2 epsi_(0))`D. `(sigma ( R + r))/(4 epsi_(0))` |
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Answer» Correct Answer - A Potential at the centre due to the sphere 1 `V_(1) = (1)/(4pi epsi_(0)) (q)/(R)` and due to sphere `2 ` is `V_(2) = (1)/(4pi epsi_(0)) (q)/(r)` `therefore ` Electric potential at the common centre `V = V_(1) + V_(2) = (1)/(4pi epsi_(0)) (q)/(R) + (1)/(4 pi epsi_(0)) (q)/(r)` `= (q)/(4 pi epsi_(0)) [ (1)/(R) + (1)/(r)] = (q)/(4 pi epsi_(0)) [( R + r)/(Rr)]` We have `(q)/(4 pi R r) = sigma therefore v = (sigma (R + r))/(epsi_(0))` |
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