# Does the current of an electrolytic cell increase if the surface area of the Cathode is increased

I am currently in high school and will be conducting an experiment looking at the effect of surface area on electroplating. I will be changing the surface area of the Cathode during my experiment but am unsure whether the amp and voltage would be controlled or dependant variables.

• For a given experimental electroplating setup, there is likely to be an optimal current density at the cathode. This is the current that flows divided by the exposed (to solution) area of the cathode. So current and cathode area are two obvious control variables, and, of course, there are others. Best of success with your project! – Ed V Feb 8 at 15:09

Just remember two major rules in electrolytic electrochemistry:

1. If you fix voltage, current cannot be controlled. This is called constant potential electrolysis

2. If you fix the current, voltage cannot be controlled. This is called constant current electrolysis

Now your electrolysis cell has resistance:

(i) It will depend on electrolytes

(ii) Surface area of the electrodes

(iii) Distance between the electrodes

So let us know your results and findings. Plot a graph systematically by choosing condition 1 or 2.

The voltage won't vary as it depends on the materials used as active electrodes and their respective standard reduction potentials. The current will vary with plate area due to varying resistance of the cathode plate.