clear steps would be helpful thank you

2) A velocity selector that can be used to measure the velocity of a charged particle. A stream of particles is directed along the axis of the instrument. A parallel plate capacitor sets up an electric field E, which is oriented perpendicular to a uniform magnetic field B. If the plates are separated by 7.567 cm and the value of the magnetic field is 36.87 mT, what is the surface charge density on the plates that will allow particles of speed 337*10^7 mm/s to pass straight through without deflection? Tube B (into paper) (cutaway x X X X view) X XXXX + + + + + X X X X X Capacitor XXXXX plates