Two concentric spheres of radii `R` and `r` have similar charges with equal surface charge densities `(sigma)`. The electric potential at their common centre is

Options

A. `sigma // epsi_(0)`
B. `(sigma)/(epsi_(0))(R - r)`
C. `(sigma)/(epsi_(0))(R+r)`
D. None of these

Answer

C

Explanation

Since both spheres have same `sigma` but are of different radii, So they have different value of charges.
`therefore V=k/(4 pi e_0) [Q/E+q/r]=1/e_0[(QR)/(4 pi R^2)+(qr)/(4 pi r^2)], V=1/e_0 [sigma R+ sigma r]=sigma/e_0[R+r]`