A point charge q is placed inside a conducting spherical shell of inner radius 2R and outer radius 3R at a distance of R from the center of the shell. Find the electric potential at the center of the shell.
Electric potential due to point charge =kqR
Electric potential due to inner surface of shell =−kq2R
and electric potential due to outer surface of shell =kq3R
V=kqR−kq2R+kq3R=kqR[1−12+13]
=k5q6R
A point charge q is placed inside a conducting spherical shell of inner radius 2R and outer radius 3R at a distance of R from the centre of the shell. The electric potential at the centre of shell will be 
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A point charge Q is placed at A at a distance R2 from center of a thick conducting shell of inner radius R and outer radius 2R as shown in figure. Point P is at distance 3R2 from centre. Field at P due to induced charges on shell is nKQR2, then n is
A point charge q is placed at a distance r from the centre O of a uncharged spherical conducting shell of inner radius R and outer radius 2R. The distance r<R. The electric potential at the centre of the shell will be
