Gas Fitter Practice Test

As the temperature of a thermistor increases, the current flow through it...

1. Increases

2. Decreases

3. Remains the same

4. Fluctuates

The correct answer is: Increases

A thermistor is a type of temperature-sensitive resistor whose resistance changes significantly with temperature. There are two primary types of thermistors: NTC (Negative Temperature Coefficient) and PTC (Positive Temperature Coefficient). In the case of NTC thermistors, which are more commonly used, as the temperature increases, the resistance of the thermistor decreases. When connected in a circuit, a decrease in resistance allows more current to flow through the thermistor, following Ohm's Law (V = IR), where voltage is held constant in a series circuit. Thus, with a drop in resistance due to the increase in temperature, the current flow through the thermistor increases. In contrast, PTC thermistors would behave differently, where an increase in temperature leads to an increase in resistance, resulting in a decrease in current. However, without additional specifications indicating the type of thermistor in the question, it is generally understood that the context is referring to the more common NTC thermistor. Therefore, the conclusion drawn—the current flow increases as the temperature increases—aligns accurately with the characteristics of NTC thermistors.