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

Options

A. `sigma//epsilon_(0)`
B. `(sigma)/(epsilon_(0)) (R -r)`
C. `(sigma)/(epsilon_(0)) (R -r)`
D. `(sigma)/(4pi epsilon_(0)) (R + r)`

Answer

C

Explanation

`V = (1)/(4pi epsilon_(0))(Q)/(R ) + (1)/(4pi epsilonL0)(Q)/(r )`
or `V = (1)/(epsilon_(0)) [(Q)/(4piR^(2))R + (Q)/(4pi epsilon^(2))r]`
`= (sigma)/(epsilon_(0)) (R + r)`