Mar 27, 2022 • 8M

What is energy?

Open in playerListen on);
Great Teachers Matter
Episode details

Scientists define energy as the ability to do work. Energy has different forms.

We live in modern times where people have learned how to transform one form of energy to another and benefit from it.  We often associate energy with our ability to remain active and do things efficiently. However, we need energy not just for walking and running; people use energy to drive all forms of vehicles, to cook food, to light their homes and offices, to produce goods and to travel to space. In short, we need energy for anything and everything we do in our day-to-day life.

Transformation of energy

There are different forms of energy, including heat, light, sound, chemical, electrical, gravitational, and motion. These can be grouped into two general types – potential or stored energy and kinetic or working energy.

Energy is transformed from one form to another to suit our various needs. Let us take a look at an example. We eat food every day. The chemical energy in the food gets stored in the body. Then this chemical energy is converted into kinetic energy and is used to perform our daily tasks.

Let us take an example of energy transformation from the power sector. Both natural gas and coal have chemical energy. The water flowing through the river has kinetic energy. All these forms of energy are converted to electrical energy during the production of electricity. Once electricity is distributed, it is further transformed into light energy, thermal energy, etc.

Different forms of energy

Most people are curious about the production of energy. The fact is that energy can neither be created nor destroyed – energy can only be transformed from one form to another. This universal principle is called the law of conservation of energy. This is also the first law of thermodynamics. When people use energy, it is transformed from one form to another.

Potential energy is the stored energy of an object or a system by virtue of its position. It is classified into different types like gravitational potential energy, chemical energy, and nuclear energy.

Mechanical energy is the energy exerted on an object by any kind of pressure.

The energy in batteries, petroleum, natural gas, biomass, etc., is chemical energy, which is stored in the form of bonds that connect atoms with other atoms, or molecules with other molecules.

Atomic energy is the energy stored in the nucleus of an atom. It is the energy that holds the nucleus in place.

Mechanical energy, which is different from the energy types mentioned above, is the energy exerted on an object by any kind of pressure. Energy in a stretched rubber band or in a compressed spring is an example of mechanical energy.

Kinetic energy is the energy of an object when its particles are in motion.

Energy due to the force exerted on objects by gravity is called gravitational energy. This depends on the weight of the object and its altitude. Gravitational energy increases with the increase in weight and altitude. For example, if a person is riding a bicycle down a slope, he or she can feel the increase in speed. This is due to the conversion of gravitational energy into kinetic energy. It is the same principle that is used in hydroelectric power stations.

Kinetic energy is the energy of an object when its particles are in motion. The motion of sea waves, and the movement of atoms and molecules in a matter are all examples of kinetic energy.

Thermal energy is generated by the movement of atoms and molecules in a substance. As the speed of this movement increases, the energy also increases. The Earth’s thermal energy is called geothermal energy.

X-rays, gamma rays, and radio waves are all sources of radiant energy. It is the physical energy resulting from electromagnetic radiation. Sunlight is also an example of radiant energy.

Energy generated by the movement of objects can be stored. As the speed increases, more energy gets stored this way. An example of this is the windmill. A windmill converts wind energy into electrical energy.

We are quite familiar with electrical energy. We have already covered the energy transformations during the production of electricity. Lightning is the best example of natural electricity.

Sound is also a form of energy. Sound forms when the force exerted on an object produces vibrations. Sound energy is a weak form of energy compared to the other forms of energy.

Energy resources

We can classify energy resources as renewable energy resources and non-renewable energy resources. As the name implies, renewable energy resources are replenished naturally while non-renewable energy are not replenished at the speed at which it is consumed. Solar energy, wind energy, geothermal energy, hydroelectric power, and biomass are examples of renewable energy resources.

When it comes to consumption, we mostly depend on non-renewable energy resources. Fossil fuels, natural gas, nuclear power, etc., are examples of non-renewable sources of energy. All of these resources are only available in limited quantities. They do not get replenished in the same speed as we consume them. Fossil fuels are formed when organic matter that was buried deep inside the Earth are subjected to heat and pressure for millions of years.

Energy efficiency

Energy efficiency simply means the elimination of wastage of energy. When energy is converted from one form to another, there is loss of energy. In some cases, after the energy exchange, energy becomes unusable. Human body is a prime example.

Let us assume that our body is a machine. Energy from food is the fuel needed to operate this machine. Our body converts this energy into various forms to perform bodily functions, but the energy efficiency of the human body is a mere 5%. The remaining energy is released from the body in the form of heat.

Now put on your thinking hats and think about the following questions for a couple of minutes. As a teacher, how do you describe the term “fossil fuel” to your students?

Can you think of any alternatives that we can use instead of fossil fuels?

In your opinion, what are the best ways to ensure energy efficiency?

Write down your thoughts and discuss them with your students, children and your colleagues. Listen to their views and compare them with your own. As you listen to others, note how similar or different your views are to others’.

Thank you for listening. Subscribe to The Scando Review on

Happy Teaching!