what is thermocouple ?

A thermocouple is a type of temperature sensor that consists of two dissimilar metal wires or elements, which are joined together at one end to form a junction. When this junction is exposed to a temperature gradient, it produces a voltage that is proportional to the temperature difference between the junction and the other end of the wires.

Thermocouples are commonly used in industrial and scientific applications for measuring temperature in environments where other types of temperature sensors might not be practical, such as high-temperature and high-pressure environments. They are also relatively inexpensive and can be made to operate in a wide range of temperatures.

There are many different types of thermocouples available, each with its own unique set of characteristics and temperature range. Some of the most commonly used types include Type K, Type J, Type T, and Type E.