Technical Standards and Safety Authority (TSSA) G3 Practice Exam

If voltage remains constant while current increases in a resistive circuit, what happens to resistance?

1. Increases

2. Remains the same

3. Decreases

4. Fluctuates

The correct answer is: Fluctuates

In a resistive circuit, according to Ohm's Law (V = IR), if the voltage remains constant and the current increases, the resistance must necessarily decrease. This relationship is fundamental to understanding how resistive circuits operate. When the voltage is held steady, an increase in current indicates that the material through which the current flows is allowing more charge to pass through per unit of time, which means the resistance (R) must be lower. In this context, resistance can be viewed as a measure of how much a material opposes the flow of electric current. If that opposition decreases while maintaining a fixed voltage, it logically follows that the resistance decreases in response to the increase in current. Thus, the correct response indicates that resistance does not remain the same (as that would imply no change in the relationship between voltage and current), nor does it increase, which would contradict the observed increase in current under constant voltage. The option of fluctuating resistance indicates instability in the circuit, which does not hold true under steady-state conditions where voltage is constant.