A light beam traveling in the negative z direction has a magnetic field B=(3.02 x 10-9T) x + (-5.28 x 10-9T) y at a given instant of time. The electric field in the beam has a magnitude of1.82 N/C at the same time. a) Does the electric field at this time have a z component that is positive, negative or zero? Describe. b) Write E in terms of unit vectors.