Cathode Ray Tube Voltages


In doing the experiment on finding effect of electric field alone on electron beam, there are two voltages supplied. One is to the cathode and anode, while the other is to the electric plates creating the electric field. Should the two voltages have a common earth? If yes, why is it necessary to have the zero voltage together?


The deflection electrode voltage should be at the common earth (cathode) potential when neutral. To deflect the beam, one plate should go positive relative to the common and the other negative relative to the common to have a symmetrical effect.