Picture an instrument similar to a mass spectrometer. In which picture, a singly-ionized atom is accelerated from rest through a potential difference, DV, until it passes through the slit, S1. The atom then enters a velocity selector in which the strength of the magnetic field, BSEL, = 4T and is directed into the plane of the paper .
The electric field strength in the selector is 4.819 x 105 N/C. The atom passes straight through the selector without any deflection of its path. It then enters the main instrument in which the strength of the magnetic field, BI, = 2 T and follows a semi-circular path whose diameter is 0.02 m.
From the information above, determine the direction of the magnetic field, BI. (indicate on the diagram)