A charge Q is distributed a uniformly on a ring of radius R as shown in the following diagram. Find the electric potential at the centre O of the ring.

Explanation

Consider a small charge dq. Electric potential at O due to dq,

`dV=(1)/(4piepsilon_(0))*(dq)/(R)`
`V_(0)=SigmadV=(1)/(4pi epsilon_(0)R)Sigmadq=(1)/(4piepsilon_(0))*(Q)/(R)`