Final answer:
Thermocouples produce a voltage when there is a temperature increase, leveraging the Seebeck effect. Thermistors, on the other hand, are resistive devices whose resistance changes with temperature and are also used for temperature measurements in various types of thermometers.
Step-by-step explanation:
Thermocouples are temperature-sensing devices that produce a voltage when the temperature increases. This is based on the Seebeck effect where a circuit made of two different metals generates a voltage when there is a temperature difference between the metals. They are often used to convert the thermal condition into electrical signals. An equivalent device for temperature measurement is the thermistor, a type of resistor whose resistance varies significantly with temperature. Unlike thermocouples that generate voltage, the resistance change in a thermistor can be measured and translated into a temperature reading. For example, a graph indicating resistance in ohms against temperature in Kelvin might show how resistance starts off constant but then sharply increases as the temperature reaches a certain threshold, reflecting the strong temperature dependence of these materials.
Similarly, when considering the temperature dependence of resistance, many thermometers are designed based on this principle. A thermistor is a common example, which is a small semiconductor crystal that achieves thermal equilibrium quickly. This allows for accurate and rapid temperature readings.