Charged particles in a vacuum are accelerated (In a device called a betatron) by the Electric Field E that necessarily accompanies a time-dependent magnetic ?eld B(t). Suppose that, in cylindrical coordinates, the magnetic ?eld throughout the betatron at time t can be approximated by B = Kr"te,, where K and n are positive constants. Assuming that the companion electric ?eld takes the form E = E;(r)e?, express E in terms of r, K and n. If the electric ?eld in the plane z = 0 is observed from a point on the positive z-axis, do its ?eld lines point clockwise or anticlockwise? Explain the answer in a sentence or two.