The quarter disc of radius R (see figure) has a uniform surface charge density `sigma`.
(a) Find electric potential at a point (O,O,Z)
(b). Find the Z component of electrif field at (O,O,Z)

Options

A. `(sigma)/(8epsilon_(0))[1-(Z)/(sqrt(R^(2)+Z^(2)))]`
B. `(sigma)/(4epsilon_(0))[(sqrt(R^(2)+Z^(2)))+Z]`
C. `(sigma)/(8epsilon_(0))[sqrt(R^(2)+Z^(2))-Z]`
D. `(sigma)/(8epsilon_(0))[(Z)/(sqrt(R^(2)+Z^(2)))]`

Answer

C