Electric Flux & Gauss's Law
A spherical conducting shell of inner radius 'r ' and outer radius 'r ' has a charge 'Q'. A charge q is placed at the centre of the shell. The surface charge density on the inner and outer surface of the shell will be

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Answer: (a)
- Field inside the conductor is zero, so the inner surface carries to cancel the central .
- Total shell charge is , so the outer surface carries .
- ,
- So the answer is (a).