An electron of mass m (9.1 times 10-31 kg) and charge q (-1.6 times 10-19 c) is accelerated to the right (in the plane of the page) from rest through a potential difference v = 1500 v. the electron then enters a region, defined by x > 0, containing a uniform magnetic field b = 0.3 t directed out of page. how much time, t (in seconds), does the electron spend in the magnetic field region?