In an electron mircoscope electrons are boiled off by an electron gun and attracted to an anode. The high voltage difference causes the electrons to accelerate. Assuming the speed of the electrons is zero as they are emitted and that as they reach the anode it is v, what is the expression relating to the final speed v to the charge on an electron, the mass of an electron and the voltage difference and hence calculate the speed v of the electrons after passing through a voltage difference of 120 kV.