Josh stored an electric potential energy of 2.5J in a vacuum of 1.00m³ by a field E. if the field is reduced to 1/4 of its initial value, how much energy is
stored per cubic meter.
Ans is 0.2J/m³

A professor accelerated an electron of mass 9.1 x 10^15N/C between two
parallel charged plates of separation 1.7cm. Calculate the velocity with
which the electron leaves a hole in the positive plate if it is accelerated near
the negative plate.
Ans is 4.2 x 10^12m/s​