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Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
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Neeraj bansal
question says that there is sphere with radius 'a' and it is surrounded with dielectric material upto radius 'b' i.e. dielectric is outside given sphere. we have to find potential at thecentre using infinity as reference point and volume and charge density. means you will assume bringing the charge from infinity to centre of sphere