Describe the pattern in potential difference when changing the number of bulbs in the circuii?

In a series circuit, adding more bulbs increases the total resistance, which causes the potential difference across each bulb to decrease, as the total voltage is divided among them. Conversely, in a parallel circuit, adding bulbs does not significantly change the potential difference across each bulb, as each one receives the full voltage of the power source. Thus, while the overall current may increase with more bulbs in parallel, the potential difference remains constant.