Answer:
The 9-v transistor battery is a direct current source, while the power supply from the wall socket is an alternating current source.
Explanation:
A direct current (DC) is one that flows continuously without any minimum and maximum values. This is majorly obtained from generators, batteries or cells etc.
An alternating current (AC) is a type that flows in a sinusoidal manner, having minimum and maximum value with respect to its flowing frequency. An example is the one obtained from the wall electrical source , generators etc.
An alternating current is not mainly used for electrolysis because of its nature. It would cause a switch of the electrodes in every cycle. Therefore, a direct current source is used.
The 9-v transistor battery is a direct current source, while the power supply from the wall is an alternating current source.