a solid sphere of radius r is charged uniformly.at what distance from it surface electric potential is half of that of at its centre.

ans:r/3

Dear shefali

we know potential outside the sphere is V1 = kQ/x     where x is the distance from the center x>r

 and potential inside the sphere V1 = kQ/2r [3-x²/r²]

 for center put x=0  Vo = 3kQ/2r

condition given is V1 = Vo/2

                      kQ/x  = (3kQ/2r)/2

                         x=4r/3

 distance from the surface is  =x-r

                                         = 4r/3 -r =r/3

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