Why is a variable resistor used in the electrolysis circuit?
you do not have. you need a simple resistance. resisting it will limit the amount of current. how much current do you want to run? what is the supply voltage? the value of the resistance you will need can be found by dividing the voltage by the desired current. Ohms law.
In electrolysis is that the resistance of the solution changes as the reaction occurs. It is desirable to carry out the reaction as quickly as possible, which means the highest possible current. in order to continue operating at the maximum current, a variable resistance in series with a DC power supply can be used. This is done commercially, as it is simple to create an automatic constant current source with electronic circuits.
Why is electrolysis used?
electrolysis occurs on a narrow voltage range. the efficiency of the process depends on many variables, including the type of electrode material (surface and substrate), the total area, the distance between the electrodes, the type and concentration of the electrolyte (for example, naoh), etc.
As the voltage between the electrodes increases, the current starts to flow at a certain cut-off voltage between the electrodes and electrolytic finished products are produced (for the electrolysis of water, these should be oxygen at the anode and hydrogen at the cathode).
As the voltage increases, the current also increases, as does the electrolytic output, to a certain extent. Once the maximum current density of the electrodes is reached (relative to the electrolysis processes), additional tension can have undesirable effects. These include heating, eroding the electrodes themselves and other things.
for a relatively small configuration with constant input voltage sources, the addition of a series resistor with the electrolytic cell ensures that the total current flowing through the cell is at the right level for optimal output results , lifetime of the electrodes, etc.
a variable resistor facilitates cell tuning for optimization. One reason is that fixed resistors are manufactured to a certain specification for their actual strength, between 5 and 10%. the setting of the final resistance of the circuit can be obtained by using a fixed resistor in series (for most resistors) with a variable resistor.