def calc_field2D(self, point):
    (x, y) = point[:2]
    (Rx, Ry) = self.point_charge_loc[:2]
    r = math.sqrt((((x - Rx) ** 2) + ((y - Ry) ** 2)))
    efield = ((point - self.point_charge_loc) / (r ** 3))
    return Vector(efield).shift(point)
def calc_field2D(self, point):
    (x, y) = point[:2]
    (Rx, Ry) = self.point_charge_loc[:2]
    r = math.sqrt((((x - Rx) ** 2) + ((y - Ry) ** 2)))
    efield = ((point - self.point_charge_loc) / (r ** 3))
    return Vector(efield).shift(point)