A point charge q'q is placed at distance 'a' from the centre of an uncharged thin spherical conducting shell of radius R=2a. A point 'P' is located at a distance 4a from the centre of the conducting shell as shown. The electric potential due to induced charge on the inner surface of the conducting shell at point 'P' is

Options

A. `(kq)/(5a)`
B. `-(kq)/(5a)`
C. `(kq)/(4a)`
D. `-(kq)/(4a)`

Answer

B

Explanation

Then net electric potential due to external charge inside the cavity and the induced charge on the surface of the cavity at any point outside the cavity is zero. If 'V' is the electric potential due to induced charge on the surface of cavity at point P
`V+(kq)/(5a)=0`
`thereforeV=-(kq)/(5a)`