Answer:
The Lightbulb is the dependent variable.
Step-by-step explanation:
The dependent variable is defined as the variable that the researcher is measuring or testing and it observes the direct effect/change brought by manipulation in the independent variable. In the given experiment, the lightbulb would be characterized as the dependent variable as it is being tested by the researcher. He controls the independent variable(by using different wires) to observe its direct impact on the way the lightbulb lits. Thus, it(lightbulb) is the dependent variable.