19. An electron travels in a straight line at constant velocity v = 500î m/s through a region that has both an E and a B field, with E =

0.25j V/m (uniform). What is the magnetic field (magnitude and direction)? A) 5.0•10-4k T B) 0.25j T C) -5.0•10-4k T D) -0.25f T E) 0.25k T