Description

for measuring e/m, the charge to mass ratio of the electron is a very simple set-up. It is based on Thomson’s method. The e/m-tube is bulb-like and contains a filament, a cathode, a grid, a pair of deflection plates and an anode. The tube is filled with helium at a very low pressure. Some of the electrons emitted by the cathode collide with helium atoms which get excited and radiate visible ….