`10^(-9)C` of charge is distributed over two concentric hollow spheres of radii 1 cm and 2 cm such that surface densities of charges are equal Find the potential at their common centre.

Explanation

Given, `q_(1)+q_(2)=10^(-9)C`
`r_(1)=1cm` and `r_(2)=2cm`
`because" "sigma_(1)=sigma_(2)`
`(q_(1))/(4pi r_(1)^(2))=(q_(2))/(4pir_(2)^(2))rArr(q_(1))/(q_(2))=(r_(1)^(2))/(r_(2)^(2))=1/4`
`rArr" "4q_(1)=q_(2)`
`:." "V_(B)-V_(A)=(1)/(4piepsi_(0))((q_(1))/(r_(1))-(q_(2))/(r_(2)))`
Substituting the values, we get
`V=540V`