Primary element of temperature and what os the unit of temperature and their working principle full details

 

Introduction:

Temperature is a fundamental physical quantity that measures the degree of hotness or coldness of an object. It is one of the most important parameters used in various fields such as science, engineering, medicine, and many more. The concept of temperature is based on the thermal equilibrium between two or more objects, and it is measured using various temperature measurement devices. In this article, we will discuss the primary element of temperature, the unit of temperature, and their working principles.

Primary element of temperature:

The primary element of temperature is the device that senses the temperature and converts it into an electrical or mechanical signal. There are various types of primary elements of temperature available in the market, such as thermocouples, RTDs (Resistance Temperature Detectors), thermistors, infrared sensors, and many more. Let's discuss some of them in detail.

Thermocouples:

Thermocouples are one of the most widely used primary elements of temperature. They consist of two different types of metals joined together to form a junction. When this junction is subjected to a temperature gradient, a voltage is generated that is proportional to the temperature difference between the two junctions. This voltage can be measured using a voltmeter and is used to determine the temperature. Thermocouples have a wide temperature range, from -200°C to 2500°C, and they are commonly used in industries such as steel, cement, and power plants.

RTDs:

RTDs are another type of primary element of temperature that are widely used in various industries. They consist of a metal wire or film that changes its resistance with temperature. When an RTD is subjected to a temperature change, its resistance changes, and this change can be measured using a Wheatstone bridge circuit. RTDs have a temperature range of -200°C to 850°C and are commonly used in industries such as food processing, pharmaceuticals, and aerospace.

Thermistors:

Thermistors are temperature sensors that consist of a ceramic or semiconductor material that changes its resistance with temperature. They are smaller in size than RTDs and have a faster response time. Thermistors have a temperature range of -50°C to 150°C and are commonly used in applications such as temperature control systems, automotive applications, and medical equipment.

Infrared sensors:

Infrared sensors are non-contact temperature sensors that measure the temperature of an object by detecting its thermal radiation. They are commonly used in applications such as temperature monitoring of industrial processes, HVAC systems, and medical equipment.

Unit of temperature:

The unit of temperature is the degree Celsius (°C) or the degree Fahrenheit (°F). The Celsius scale is based on the freezing and boiling points of water, where 0°C is the freezing point and 100°C is the boiling point. The Fahrenheit scale is based on the freezing and boiling points of a mixture of ice, water, and salt, where 32°F is the freezing point and 212°F is the boiling point.

In addition to these scales, the Kelvin scale is also used to measure temperature. The Kelvin scale is an absolute temperature scale, where 0 Kelvin (0 K) is the absolute zero temperature, which is the point at which all molecular motion ceases. The Kelvin scale is used in scientific and engineering applications, and it is related to the Celsius scale as follows: K = °C + 273.15.

Working principle of temperature measurement devices:

The working principle of temperature measurement devices depends on the type of primary element used. Let's discuss some of the commonly used temperature measurement devices and their working principles.

Thermocouples:

The working principle of thermocouples is based on the Seebeck effect, which states that when two differen