Two point charges are lying on the y-axis as in the figure: q1 = −4.50 μC and q2 = +4.50 μC. They are equidistant from the point P, which lies on the x - axis. (a) What is the magnitude of net electric field at P? (b) A small object of charge q0 = 7.80 μC and mass m = 1.17 g is placed at P. When it is released, what is the magnitude of its acceleration?