A proton accelerated by a potential difference of 10kV and passes horizontally into a region in which there is a uniform magnetic field B = 1.2T. Calcultae the strength of the smallest electric field, to be set up over same region, that will allow the proton to pass through undeflected.

a) First find the speed of the proton at the end of the accelerating potential differnce.

b) Use the caculated speed as the entry speed when proton enters the cross field region.