A thin non-conducting ring of radius R has a linear charge density = 0 cos , where 0 is a constant, is the azimuthal angle.

A thin non-conducting ring of radius R has a linear charge density λ = λ0 cos φ, where λ0 is a constant, φ is the azimuthal angle. Find the magnitude of the electric field strength
(a) At the centre of the ring;
(b) On the axis of the ring as a function of the distance x from its centre.
Investigate the obtained function at x >>R.