Chapter 26 : Concept of Temperature - Diploma in Engineering - Student's Corner


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Friday, January 26, 2024

Chapter 26 : Concept of Temperature - Diploma in Engineering

 Chapter 26 : Concept of Temperature

Temperature is a fundamental physical quantity that characterizes the degree of hotness or coldness of an object. Understanding temperature and its accurate measurement is crucial in various scientific, industrial, and everyday applications. In this chapter, we delve into the concept of temperature, explore the scales used for measurement, and discuss the methods employed to measure temperature accurately.

Concept of Temperature

Temperature is a measure of the average kinetic energy of the particles in a substance. In simpler terms, it reflects how fast the particles are moving. When particles move faster, the temperature is higher, and when they move slower, the temperature is lower. The three most commonly used temperature scales are Celsius (°C), Fahrenheit (°F), and Kelvin (K).

1.   Celsius (°C): The Celsius scale is based on the properties of water. Zero degrees Celsius is defined as the freezing point of water, and 100 degrees Celsius is defined as the boiling point of water at standard atmospheric pressure.

2.   Fahrenheit (°F): The Fahrenheit scale is commonly used in the United States. It also uses the freezing and boiling points of water, but the scale places these at 32°F and 212°F, respectively.

3.   Kelvin (K): The Kelvin scale is an absolute temperature scale used in scientific applications. It starts from absolute zero, the point at which particles have minimal motion. The Kelvin scale is widely used in physics and chemistry.

Methods of Temperature Measurement

Several methods are employed to measure temperature accurately, each suited to specific conditions and requirements. Some common methods include:

1.   Thermocouples: Thermocouples are temperature sensors based on the Seebeck effect, where a voltage is generated across a junction of two different metals in response to a temperature difference. They are versatile and find use in a wide range of applications.

2.   Thermistors: Thermistors are temperature-sensitive resistors that exhibit a significant change in resistance with temperature. They are often used in electronic circuits and are highly sensitive to small temperature variations.

3.   Infrared Thermometers: These non-contact devices measure the infrared radiation emitted by an object. They are commonly used in industrial settings and for medical purposes, providing quick and remote temperature readings.

4.   Bimetallic Temperature Sensors: Bimetallic strips consist of two different metals bonded together. As the temperature changes, the metals expand or contract at different rates, causing the strip to bend. This bending can be calibrated to indicate temperature.


Understanding temperature and its accurate measurement is essential in various scientific, industrial, and daily life scenarios. The choice of temperature scale and measurement method depends on the specific requirements of the application. Advances in technology continue to enhance our ability to measure temperature with precision, contributing to advancements in fields ranging from physics to healthcare.