Need Help?

Get in touch with us


Understanding Thermal Energy: What It Is and How It Works

Sep 7, 2023

Thermal energy is essential to our daily lives, from warming our homes in winter to powering our industries and transportation. It is a form of energy generated by molecules’ movement in a substance due to its temperature. Understanding thermal energy and its workings is important in various domains, including engineering, physics, and environmental science. 

What is Thermal Energy?

Thermal energy, also known as heat energy, is generated due to an increase in temperature that leads to faster movement and collisions of atoms and molecules. The molecules in a substance are in constant motion, and the amount of energy they possess is directly related to their temperature. Thermal energy can be transferred from one object to another through heat transfer mechanisms such as conduction, convection, and radiation.


Types of Thermal Energy

Thermal energy can exist in different forms, depending on the nature of the substance and the way it is heated or cooled. The following are the four main types of thermal energy:

Internal Energy

This is the energy possessed by the molecules of a substance due to their motion and position. It is the sum of the kinetic energy and potential energy of the molecules in the substance. The internal energy of a system represents the total energy possessed by its particles, including their kinetic and potential energies. By adding or removing heat from the system, the internal energy can be increased or decreased, respectively.


Sensible Heat

This refers to the energy that a thermometer can detect or sense. Sensible heat causes a change in the temperature of a substance without changing its phase. For example, when a pot of water is heated on a stove, the temperature increases due to the transfer of sensible heat from the stove to the pot.

Latent Heat

This is the energy required to change a substance’s phase without changing its temperature. When a substance changes its phase from solid to liquid or gas, the latent heat is either absorbed or released. For example, when ice melts into water, the heat energy required to break the bonds between the ice molecules is the latent heat of fusion.


Chemical Energy

This energy is stored in the bonds between atoms and molecules. When a chemical reaction occurs, the energy is released in the form of heat. Chemical energy is commonly used in combustion reactions, such as burning fuel to generate heat or electricity.

Measuring Thermal Energy

Measuring thermal energy is important in many applications, such as monitoring the performance of heating and cooling systems or calculating the energy needed for industrial processes. 


The standard unit of thermal energy is the joule (J), which is the energy required to raise the temperature of 1 kilogram of water by 1 degree Celsius. Another common unit of thermal energy is the calorie (cal), defined as the energy required to raise the temperature of 1 gram of water by 1 degree Celsius. In some applications, larger units such as kilojoules (kJ) or megajoules (MJ) may be used. (1 kilojoule is equal to 1000 joules, and 1 megajoule is equal to 1,000,000 joules)

The amount of thermal energy in a substance can be calculated using the following formula:


Q = m × c × ΔT

Where Q is the amount of thermal energy, m is the mass of the substance, c is its specific heat capacity, and ΔT is the temperature change. The specific heat capacity is the amount of energy required to raise the temperature of 1 kilogram of a substance by 1 degree Celsius.


Transfer of Thermal Energy

Thermal energy can be transferred from one substance to another through several mechanisms. The following are the three main ways in which thermal energy can be transferred:


This is the process by which heat energy is transferred through a material due to a temperature difference between two regions. In this process, the heat energy is transferred from the hotter to the cooler regions of the material, resulting in a gradual equalization of temperature throughout the material. Metals are good conductors of heat, while materials such as plastics and wood are poor conductors.



This transfers heat energy by moving fluids, such as liquids or gases. When a fluid is heated, its density decreases, causing it to rise and cooler fluid to replace it. This movement of fluids transfers heat energy from one region to another. Convection is the primary mechanism for heat transfer in liquids and gases.


This is the transfer of heat energy through electromagnetic waves, such as visible light, infrared radiation, and radio waves. Unlike conduction and convection, radiation can occur in a vacuum and does not require the presence of a material medium. All objects emit and absorb radiation; the amount of radiation emitted depends on the object’s temperature. Radiation is the primary mechanism for heat transfer in space and is the basis for the operation of solar panels.

Conservation of Thermal Energy

Thermal energy conservation is an important concept in science and engineering that involves transferring and transforming heat energy. The first law of thermodynamics states that energy cannot be created or destroyed. Still, it can be transformed from one form to another. This law applies to all forms of energy, including thermal energy, and is essential in understanding the transfer and transformation of thermal energy in various systems.


Understanding the principles of thermal energy and its conservation is critical in ensuring we use energy efficiently and sustainably. Reducing energy waste and improving energy use efficiency can help mitigate climate change, save money on energy bills, and create a more sustainable future.

Frequently Asked Questions

What is the difference between thermal energy and temperature?

Thermal energy is the total energy possessed by a system due to the movement of its particles. At the same time, temperature measures the average kinetic energy of the particles in a system. In other words, thermal energy is a measure of the total heat content of a substance, while temperature is a measure of the intensity of the heat in a substance.

How is thermal energy generated?

Thermal energy can be generated through various means, such as the combustion of fossil fuels, nuclear reactions, geothermal energy, and solar energy. It can also be generated by transforming other forms of energy, such as mechanical or electrical energy.

What are some examples of thermal energy in everyday life?

Some examples of thermal energy in everyday life include the warmth of the sun, the heat generated by an oven or stove, the warmth of a cup of coffee, and the heat generated by a car engine.

Thermal Energy


Relevant Articles

Avogardo’s Number

Avogadro’s Number: Meaning, Importance, and More

Introduction The concept of measuring the microscopic particles that make …

Avogadro’s Number: Meaning, Importance, and More Read More »

Types Of Circuits

Types Of Circuits

Electricity has a critical place in modern society. It has …

Types Of Circuits Read More »

Kinetic Friction

Kinetic Friction – Definition, Laws, Types

Kinetic Friction Kinetic force is a force acting between two …

Kinetic Friction – Definition, Laws, Types Read More »


Study Abroad

card img

With Turito Study Abroad

card img

With Turito Study Abroad

card img

Get an Expert Advice from Turito

card img

Get an Expert Advice from Turito


card img

With Turito CAP.


card img

With Turito Coding.


card img

With Turito RoboNinja


card img

1-on-1 tutoring for the undivided attention