My question: Suppose the electric field is switched off when a charge is moving with a certain velocity (no acceleration) in it. What will be its velocity with time after the field is made zero ? There is no external magnetic field considered. Your Reply 1 If the E field is always zero, there is no net field all the time, then the net force is zero. But if the E field exists, at the time it is being turned off. We need to know the rate of change of the E field: (dE/dt , which will create a magnetic field. ) to calculate the effect. My reply 1 Assume that the Efield is a steady constant field.