Three concentric metallic spherical shells `A,B` and `C` of radii `a,b`and `c(a lt blt c)` have surface charge densities `-sigma ,+sigma `and -sigma `respectively ,the potential of shell `A` is

Options

A. `(sigma//epsilon_(0))[a+b-c]`
B. `(sigma//epsilon_(0))[a-b+c]`
C. `(sigma//epsilon_(0))[b-a-c]`
D. none

Answer

C

Explanation

`V_(c)=K((-qc)/(c)+(q_(B))/(b)-(q_(A))/(a))`
`V_(A)=(1)/(4piepsilon_(0))[-(sigma4pic^(2))/(c)+(sigma4pib^(2))/(b)-(sigma4pia^(2))/(a)]`
`=(sigma)/(epsilon_(0))(b-c-a)`