Given charge distribution on the surface
is shown in the figure. Symmetry of this distribution implies that the sought
at the centre O of the sphere is opposite to vector a.
![](https://www.sarthaks.com/?qa=blob&qa_blobid=9244281393811155938)
Again from symmetry, field strength due to any ring element vector dE is also opposite to
![](https://www.sarthaks.com/?qa=blob&qa_blobid=15156222872818898935)
![](https://www.sarthaks.com/?qa=blob&qa_blobid=1496608437971695437)