Fundamentals : Work done by electric field

Work done by eletcric field . qV = change in KE. Very often the initial KE is zero and hence for an electron eV= 1/2 mv2. If the initial velocity is non zero, then the equation should be written as eV = KEf- KEi. There is loss incease in KE and decrease in electric potential energy when electron move in opposite directrion to E.