The electric field due to a point charge of strength q at the origin has a potential function vequalsstartfraction kq over r endfraction , where is the square of the distance between a variable point p(x, y,z) and the charge, and kgreater than0 is a physical constant. the electric field is given by eequalsminusgradientv, where gradientv is the gradient in three dimensions. complete parts a and b.