- #1
TobeHode
- 11
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Homework Statement
Hello. I am having trouble understanding the simple circuit diagram that is attached.
I need to explain what the function of the two resistors are. I know some basic things about circuits (Ohms law, Kirchoffs loop rules,etc.) but I do not know exactly how a vacuum tube functions in a circuit.
Hint: Consider the energy of the electrons leaving each end of the filament.
Sorry about the diagram, I made it in paint. The line connecting the resistors to ground does not connect to either line going to filament power. I tried to indicate this.
Homework Equations
The Attempt at a Solution
So here is what I do know. There is a tungsten filament (the cathode) that heats up and when the temperature gets hot enough, electrons are emitted (thermionic emission) creating a space charge around the filament. By applying a positive potential to the anode, the flow of electrons will go from cathode to anode resulting in a current.
The purpose of this circuit was to show the characteristics of thermionic emission. Various values of filament current (the A ammeter) and filament voltage was used to record the anode current (the mA ammeter) for a range of anode voltage.
The potential is different at each end of the filament. In regard to the hint, this make me think that the resistors somehow negate the effect of having different potentials at each end of the filament. How this happens, I do not understand.
I am not looking for a flat out answer, rather some insight into how this circuit functions. I think If I can get an idea of how exactly the current flows then I should be able to answer the original question.