A positive charge q is fixed at the point x = 0, y = 0, and a negative charge - 2q is fixed at the point x = a, y = 0.
(a) Show the positions of the charges in a diagram.
(b) Derive an expression for the potential V at points on the x-axis as a function of the coordinate x. Take V to be zero at an infinite distance from the charges.
(c) At which positions on the x-axis is V = 0?
(d) Graph at points on the x-axis as a function of x in the range from x = -2a to x = +2a.
(e)What does the answer to part (b) become when x » a? Explain why this result is obtained.