Each of the power supply outputs serves a key purpose in the apparatus. The heater voltage heats the cathode so that it will produce enough electrons. For instance, if the heater voltage is too low then the experiment will not work out because the cathode will heat a filament enough so that it will emit enough electrons for anything to be measured. Whereas, if the heater voltage is too high then the filament could blow or the neon atoms could ionize.

The second channel controlled the control grid voltage. This voltage was not as tricky to set as the heater voltage because primary purpose was to attract the electrons from the filament to the grid so that the experiment can be observed.

Lastly, the reverse bias voltage from the power supply was another key voltage to set. To illustrate its function, if the reverse bias voltage was too low in magnitude NOT TRUE. should read TOO HIGH IN MAGNITUDE, NOT TOO LOW IN MAGNITUDE then the electrons would not be attracted towards the plate measuring the number of electrons which produced the graph that allows us to study the discrete energy levels of neon.