Physics Magnetism,Magnetic Effects Of Current Level: High School

A proton is fired with a speed of 1.0 x 10^6 m/s through the parallel-plate capacitor shown in the figure at 'click here'. The capacitor's electric field is E = (1.0 x 10^5 V/m, down)

a) What magnetic field B , both strength and direction, must be applied to allow the proton to pass through the capacitor with no change in speed or direction ?