Determine the electric field strength vector if the potential of this field depends on x, y coordinates as a) = a(x 2 y2); (b)

Determine the electric field strength vector if the potential of this field depends on x, y coordinates as
a) φ = a(x 2 – y2);
(b) φ = axy, where a is a constant. Draw the approximate shape of these fields, using lines of force (in the x, y plane).