The laws of conservation of energy are basically the principles, governing all the energies existing in the universe. The statement of the law is given for a closed system as ‘energy can neither be created nor destroyed-it transforms from one form to another’. Energy flowing through or passing by different systems has typical behavior which has been interpreted by the law. As this is a fundamental natural law, energy conservation should be well understood in order to explain the transmission of energy, its storage and usage in mankind
Conservation simply means that the environment encounters no alterations. A parameter representing a conserved quantity always remains constant over time. Therefore, if any event occurs in the environment, the value of that quantity still remains unchanged. There are various entities in physics which must be constant to hold the law of conservation. The parameters like energy, momentum, spin, angular momentum etc. must be conserved to obey the rule. The calculation of these quantities helps in several predictions and makes those complex events much simpler.
What is the Law of Conservation of Energy?
The Law of Conservation of Energy also states that the total energy of an isolated system is equal to the sum of its kinetic and potential energies. Whatever changes may occur in forms of energy, we find the total amount of energy the same at the end in that system. This law is obeyed by all mechanisms like rubbing of hands to flow electrons in wires. Any law that violates the law of energy conservation meets a failure.
To describe the mechanism in simple words, when energy is found to be to be lost in one form, it is actually changed into another. For example, when we switch a light bulb, the electrical energy is turned into light energy, and we are able to view objects in the dark. The total energy in the process remains constant and has simply been transformed from one form to another.
This law stands as a basic foundation to many areas of physics, including mechanics, thermodynamics, electromagnetism, nuclear physics and even quantum mechanics. It has broad implications from daily life to electronics, engineering, environment science, and cosmology.
How Does Energy Change Forms?
Energy conversion, also known as energy transformation, is the process of converting one type of energy into another. The conversion of energy happens at all times of the day. There are several types of energy, for example thermal energy, electrical energy, nuclear energy, electromagnetic energy, mechanical energy, chemical energy, and sound energy. Similarly, we may understand the word Energy Transformation as the process where a form of energy is worked out and emerges as a new form. The law of conservation of energy applies at the end to the total energy and remains fixed, regardless of whether energy is transformed or transferred. A branch in physics i.e. thermodynamics, studies about the conversion of energy whose first law is the statement of law of conservation of energy. It makes clear how the entropy (disorderness) of the closed system remains constant. Some of the types of energy and the process of how conversion happens is given below:
- Mechanical Energy
Mechanical energy is the type of energy associated with the position and momentum of an object. An object possesses two kinds of energy: kinetic energy when the object is in motion and potential energy when the object is resting at a position. When a car moves, it has kinetic energy from its speed and potential energy from its initial position. As the car comes in motion, its potential energy drops and its kinetic energy increases. Again, when the car comes to rest after travelling a certain distance, again its total energy remains as potential.
- Thermal Energy
As we know all matter is composed of atomic and subatomic particles, the inter-molecular motions of these matters give rise to thermal energy. When particles are heated the molecules and atoms move vigorously and the material acquires more thermal energy. The motions are generally of three types: rotational, translational and vibrational. As it is the energy of the atoms and molecules in motion, it can also be called their kinetic energy. Thermal energy can also be transformed into other forms of energy. For example, in a steam engine, thermal energy is converted to mechanical energy.
- Chemical Energy
It is the potential energy contained inside the chemical bonds, atoms and subatomic particles. The energy exchange occurs during a chemical reaction and can be observed and measured from there. After a chemical reaction either the energy is absorbed or released. For example, fuel and petroleum have stored chemical energy which gets converted into heat, light or other forms of energy after combustion.
- Electrical Energy
The flow of electrons inside a conductor causes electrical energy. It can also be known as the kinetic energy of electrons as electrons are in motion. This form of energy is seen in every home appliance. All negatively charged electrons flow in the same direction and develop an electric current in the conductor. It is a secondary energy source that is converted from other primary forms of energy like wind energy, solar energy etc. by a generator. For example, the nuclear power plants convert nuclear energy into electrical energy. This electrical energy has wide applications like charging of phones to power electronics
- Nuclear Energy
Nuclear energy is the energy released when two nuclei of atoms are bombarded. We call it nuclear fission when a heavy nuclei is splitted into light nuclei. Similarly, when light nuclei combine to form a heavy nucleus, it is called nuclear fusion. A tremendous amount of energy is released in these cases. Both types of reactions are utilized to extract energies in high amounts by nuclear power plants and transform it into other forms like electrical energy, electromagnetic energy etc.
- Sound Energy
Physical vibrations transferred through mediums like air, water, or other materials produce sound energy. It is also a kinetic energy as it involves motion of air particles or molecules. When we produce sound either speaking or hitting on something or maybe tuning a musical instrument the mechanical energy changes into sound energy. When sound waves travel through the air, the energy carried by them can be transformed into other forms, like thermal energy and electric energy.
- Radiation Energy
Radiation energy is the energy carried by electromagnetic waves like light waves, radio waves, X-rays and gamma rays. The Sun is regarded as the primary source of all kinds of thermal energies and is the best example of radiation energy. Solar energy is converted into thermal energy that provides all the required heat to the planets. There are other radiation energies like cosmic microwave backgrounds which have been found since the evolution of the universe. In each of these cases the energy has been transmitted to different forms, but the total energy of the closed system is the same. Here the universe is regarded as a closed system.
Everyday Examples of Energy Conservation
We all rely on energy during our lifetime. It’s just an energy conversion which makes it easier from digestion of food to playing with modern technologies. Below are some everyday examples of energy conservation.
- Driving of car
When you drive a car, the fuel is used. The chemical energy stored in fuel is transformed into mechanical energy and thermal energy, which turns the vehicle and moves it forward. As you give a brake, the mechanical energy of the moving vehicle is converted into heat energy by the friction of the brakes. In the process some energy may be lost in the form of sound energy.
- Digestion of food
The digestion of food is a complex process. The food molecules undergo several phases of chemical reaction and the chemical energy stored in food is used to function a human body. Thus we can say a chemical energy is transformed to mechanical energy in the body.
- Burning of wood
When wood is burnt, the chemical energy stored in the wood is converted to heat and light energy. It is used for various purposes like heating on cold days, cooking and various other purposes.
- Charging a Phone
When we connect the charger to the phone or laptops or any other chargeable devices, the charger passes electrical energy to the battery of that device. The battery stores the electrical energy as a chemical energy. When the device is operated, the chemical energy is further converted into electrical energy, which runs the device.
- Induction Cookware
When the induction is connected to the power supply, electrical energy is converted to heat energy which is used for cooking purposes.
Why is Energy Conservation Important?
Energy conservation is a foremost need today. Since non-renewable sources of energy are limited, their consumption must be limited and alternatives should be taken for them. Green energy sources are likely to be brought forward for sustainable energy. Below are some major reasons to look for energy conservation.
- Environmental Impact
Higher dependence on non-renewable sources of energy degrades the environment. Burning of fossil fuels may result in the release of toxic gases like carbon dioxide which results in climate change. Thus with no use of such energy sources we can reduce negative impacts on the environment.
- Reducing Energy Costs
Energy conservation helps to reduce the energy costs like costly fuels and electricity bills. This helps in maintaining household to business expenses.
- Sustainability
Energy conservation is very important to meet sustainable energy standards. We can make more use of renewable sources so that natural energy can be saved for future generations.
- Improved Efficiency
Energy conservation also points towards the use of better technologies. By limiting energy consumption required for a purpose, like using LED lights in place of high power CFL bulbs and tube-lights, we can get more efficiency at a lower price.
Common Misunderstandings About Energy Conservation
On the contrary of energy conservation being a profound law in science, people are still confused about certain facts. Some common misconceptions are listed below:
- Energy is Lost
In certain cases it seems like energy is lost. However while observing deeply energy is always found around and is simply transformed. For example, when a bike is ridden, it seems like energy is lost, but in reality it is turned to heat energy which is lost to the surroundings and not only used to create a motion.
- Energy Conservation Means Using Less Energy
Energy conservation not only means reducing the consumption of energy. It also indicates the use of green energy sources and lower the use of natural energy sources like fossil fuels, petroleum products etc.
- Energy Can Be Created or Destroyed
It is misunderstood that energy can be created or destroyed. Energy conservation is a universal law and all the energy is used from the surrounding and again is lost to the surrounding. So, nothing about creation and destruction comes into action.
Experiments Demonstrating Energy Conservation
There are many simple experiments that can demonstrate the law of conservation of energy. Here are a few:
- Projectile Motion
When a projectile is launched from ground, it acquires a kinetic energy. It reaches its maximum height where the kinetic energy becomes zero and its total energy is the potential energy. Again due to gravity the ball experiences a free fall to the ground and some energy may be lost due to friction in the process. Thus the total energy is the sum of kinetic and potential energy.
- Heat Engine
An ideal heat engine is a theoretical engine that converts all of the heat energy to mechanical energy and has 100% efficiency. However, a practical heat engine is impossible as some of the energy is lost to overcome friction. We can demonstrate energy conservation through heat engines.
- Rubbing Hands Together
It is the simplest demonstration of energy transformation. When we rub our hands, we feel heat generated in our hands. Here, the mechanical energy while rubbing hands is being converted to heat energy. The total energy in this case also remains constant.
The History Behind the Law of Energy Conservation
The concern on energy conservation began during the 17th century. The concept was worked on for several periods to be fully developed as a strong universal theory. The point started when some Greek philosophers like Empedocles claimed that the natural elements like air, water, earth and sun were timeless and they couldn’t be created or destroyed. In the 1700s, Galileo Galilei and René Descartes built up a foundation for the law by studying the motion of objects and the mechanical energy of matter. Descartes, after his study, stated that the total quantity of motion remains constant in the universe. This initiated a base for the future studies.
In the 1800s vast research and studies were done on this topic. Scientists started to explore a relationship between work, mechanical energy and heat. Émilie du Châtelet focused on the equation that energy of an object is proportional to the mass and square of its velocity and talked only about the case when the object is in motion.
In the 1900s, the law was fully developed by a German physicist Julius Robert von Mayer. He proposed that heat and mechanical energy could be transformed to one another. He studied the law on the basis of comparison between thermal machines and respiration of animals. In the same period, James Prescott Joule conducted experiments showing that energy can be converted from motion to heat. Later, Hermann von Helmholtz deeply studied and expanded the experimental findings as the universal idea. These findings and discoveries led to the development of a new branch of physics known as thermodynamics. Today this law has an impact on all sectors of physics like nuclear physics, particle physics and quantum mechanics.
How Energy Conservation Applies to Technology Today
Energy conservation is important in the advancement of technology. The basics of this law are found everywhere, from electricity generation through power plants and propulsion of rockets to replacing non-renewable energy sources by renewable sources.
- Renewable Energy Sources
Solar, wind, hydropower, and geothermal power are sustainable energy sources that help reduce the demand of fossil fuels. These sources collect natural energy and convert it to electricity. This conserves the use of resources, presenting the idea of energy conservation.
- Energy-Efficient Technologies
The development of cost-effective technology, like electric and solar home appliances and environment friendly vehicles, leads to the decrease in high demand of energy. These technologies help in increasing efficiency of work and reduce pollution also helping in energy conservation.
- Smart Grids
With the help of smart grids, the electricity distribution is made digital, which makes the task efficient. Use of smart grids also helps to reduce pollution from some energy sources and find the certain area where the energy demand is higher.
Conclusion
The law of conservation of energy goes through the behavior of energy and gives a conclusion that energy is timeless. We have to note that the production and destruction of energy is impossible. This law governs a basic phenomenon of throwing a ball to the complex motion of elementary particles like leptons, hadrons, quarks etc.
As we see that depletion of energy is the major problem today, energy conservation is the topic of concern. It helps to reach sustainable development also by lowering the negative impacts on the environment. Thus, the thorough study of the law of energy conservation helps to understand the basic natural phenomenon and build improved technologies to perform any tasks smoothly. (Also read about Black Body Radiation)
References
Hecht, E. (2008). Energy conservation simplified. The Physics Teacher, 46(2), 77-80.
L.D. Landau and E. M. Lifshitz, The Classical Theory of Fields (Addison-Wesley, Reading, MA, 1965), p. 28.
Oliveira, A. R. (2014). History of two fundamental principles of physics: least action and conservation of energy. Advances in Historical Studies, 3(2), 83-92.
Badur, J. A. N. U. S. Z. (2015). Energy–conversion, conservation and management. Transactions of the Institute of Fluid-Flow Machinery.
Hamam, H. (2020). Principle of conservation of energy and modern theories. Physics Essays, 33(4), 444-452.
https://byjus.com/physics/law-of-conservation-of-energy/
Law of Conservation of Energy
