A Level Physics Practice Exam

What is a key characteristic of the expected temperature response of a thermistor?

1. It remains constant with temperature change

2. It increases resistance with temperature

3. It decreases resistance with temperature

4. It emits heat when voltage is applied

The correct answer is: It decreases resistance with temperature

Thermistors are temperature-sensitive resistors, and a key characteristic of their behavior is their resistance response to temperature changes. Specifically, thermistors typically exhibit a decrease in resistance as the temperature increases. This is particularly true for negative temperature coefficient (NTC) thermistors, which are commonly used in applications where monitoring temperature is crucial. As the temperature rises, the increased thermal energy allows charge carriers within the thermistor material to move more freely, resulting in lower resistance. This characteristic makes NTC thermistors useful for temperature sensing and regulation, as the change in resistance can be translated into a temperature reading. In contrast, positive temperature coefficient (PTC) thermistors behave oppositely, where the resistance increases with temperature; however, the most common type referenced in this question is the NTC thermistor. This understanding of thermistors is important in various practical applications, such as temperature sensors in electronic devices, where a responsive and reliable change in resistance is required to accurately gauge temperature changes.