Q3. (a) Four equal point charges Q [C] are positioned at locations P?(2?, 0,0), P?(-2a, 0,0), P?(0, a, 0), and P?(0, -a, 0), in the Cartesian coordinate system, as shown below. Determine the electric potential V at any point on the z axis? (5 marks)
(b) Using the result of part (a), determine the z component of the electric field at any point on the z axis. (4 marks)
(c) For z >> a, the four charges described in (a) can be replaced by a single point charge Q' at the origin. Determine the value of Q' in terms of Q. (2 marks)