During discharge tube experiment, the cathode rays are emitted from cathode at very low pressure...it is said that these rays move at very high velocity(if we apply high Potential Difference between 2 electrodes)...do these rays( stream of electrons) travel in uniform velocity or aren't they accelerated due to presence of external electric field???why do we directly find out the velocity of electron by the formula v=sq.rt(2*p.d.*e/m) ??? i am confused whether the velocity of electrons is uniform or it is being accelerated by the external electric field??