In a region of space an electric field given by E=Ek and some unknown magnetic field exists. A particle of charge q is observed to move in the x direction at a constant velocity v = vi in this region. Which of the following is a possible value of the magnetic field? Assume that only electric and magnetic forces act on the particle.
a) B = -(EX)j
b) B = +(E/v) j
c) B = -(E/V) i
d) B = -(E/V)k
e) None
