• Engineering and Architecture
  • Management and Business Administration
  • Medicine and Allied Sciences
  • Law
  • Animation and Design
  • Media, Mass Communication and Journalism
  • Finance & Accounts
  • Computer Application and IT
  • Pharmacy
  • Hospitality and Tourism
  • Competition
  • School
  • Study Abroad
  • Arts, Commerce & Sciences
  • Learn
  • Online Courses and Certifications
Energy - Definition, Types, Difference, FAQs

Energy - Definition, Types, Difference, FAQs

Edited By Vishal kumar | Updated on Jul 02, 2025 04:29 PM IST

Have you ever thought about why a Bicycle moves when you press a pedal or why our body feels heat when we sit in the sun? These events occur because of Energy. The fact is that Energy can never be lost, and it is present in various forms. In this article, we will discuss energy in detail to understand the activities happening in everyday life.

This Story also Contains
  1. What is Energy?
  2. Sources of Energy
  3. Energy Conservation Law
  4. What are the different forms of Energy?
Energy - Definition, Types, Difference, FAQs
Energy - Definition, Types, Difference, FAQs

What is Energy?

Energy Definition in Physics: The ability to do any work or cause any changes is called Energy. Energy exists in various forms, such as heat, light, electrical, chemical, and kinetic energy.

Unit of Energy

S.I. unit of energy is Joule (J). Energy is also expressed in many other non-SI system units. Many of these units include calories, ergs, kilowatt-hours, kilocalories, and British Units Thermal.

Examples of Energy

  • When you lift a book, you’re using energy to move it.
  • The sun provides energy in the form of light and heat, which warms our planet and enables plants to grow.
  • Batteries store chemical energy, which powers devices when converted into electrical energy.

Sources of Energy

Sources of energy are the various forms from which we obtain energy in our daily life. These energy sources are classified into various forms:

Renewable energy sources

Energy resources that are present in abundant amounts in nature and won't be extinct are called Renewable energy resources. Some of the examples of Renewable energy sources are - Solar energy, Wind Energy, Hydropower, Biomass, and Geothermal Energy.

Also Read

Non-renewable energy sources

These types of energy sources are finite, which means it cannot be replenished easily as they are used up. They are less organic than renewable energy sources. Examples of non-renewable energy sources are- Coal, Nuclear Energy, Natural Gas, and Oil.

Secondary energy sources

Energy resources that do not occur naturally but can be generated from the primary resources available like coal, natural gas, solar, and wind are called Secondary energy sources. Examples of such resources are- Electricity, Refined Fuels like diesel, kerosene, and many others.

Energy Conservation Law

According to Law of Conservation of Energy- "An energy can neither be created nor destroyed, it can only transformed from one form to another." The total amount of energy in a closed system remains constant over time.

Related Topics

NEET Highest Scoring Chapters & Topics
This ebook serves as a valuable study guide for NEET exams, specifically designed to assist students in light of recent changes and the removal of certain topics from the NEET exam.
Download E-book

What are the different forms of Energy?

There are many different types of energy, which fall into two main categories: Potential energy and Kinetic energy. Let's look at the different types of energy and their respective examples.

Mechanical Energy

The mechanical energy $(M E)$ of an object is given by:

$$
M E=K E+P E
$$

where:
- $K E=$ Kinetic Energy, calculated as $\frac{1}{2} m v^2$,
- $P E=$ Potential Energy, calculated as $m g h$ (for gravitational potential energy),

Kinetic Energy

Kinetic force can be defined as the force of motion. When an object is in a state of motion, it is said to have kinetic energy. For example, running water, a moving ball, and more.

The formula to calculate Kinetic energy is:

$$
K E=\frac{1}{2} m v^2
$$

where:

  • $m=$ Mass of the object (in kilograms, kg),
  • $v=$ Velocity of the object (in meters per second, $\mathrm{m} / \mathrm{s}$ ).

Chemical Energy

Energy is stored in the bonds of chemical compounds, such as molecules and atoms are called as Chemical Energy. Chemical energy is a form of potential energy because it depends on the position and arrangement of atoms within molecules. Once the chemical energy is released from an object, it is usually converted into something completely new.

Light energy

Light energy is a type of electrical radiation. Light contains photons produced when the atoms of an object heat up. Light travels in waves and is the only source of energy visible to the human eye.

Light is made up of photons, which are small packets of energy. When the atomic matter is heated, photons are produced by the movement of atoms. Photons are produced according to the temperature of an object.

Heat Energy

Heat energy can also be called thermal energy, which is produced when rising temperatures cause molecules and atoms to move faster and more precisely. Examples of hot energy are heat from the sun, a cup of hot chocolate, baking in the oven, and heat from a heater.

Frequently Asked Questions (FAQs)

1. What is Gravitational Energy?

Gravity is stored at the height of an object

 e.g. high gravity is stored on heavy and elevated objects. When someone climbs into a cliff and picks up speed, the force of gravity turns to the force of motion. Hydropower is another example of gravity, in which gravity forces water down a propeller to provide electricity.

2. What is Motion Energy?

Motion power is stored within the flow of objects. As soon as they go, a lot of energy is saved. It takes energy to persuade a moving object, and energy is released when the object is slow-moving. The wind is an example of the power of movement. A striking example of the force of movement can be a car collision - The car puts on a complete stop and releases all its movement power without delay in an uncontrolled moment.

3. Where Does the Energy Come From?

According to the law of conservation, "Energy is not created, or destroyed, but can be changed from one form to another."

The energy we use is simply the conversion of other species. It has no specific sources. However, most of the energy we have used is the result of the Sun.

Looking at the representation above, it is clear that we need power. We get this energy from eating food, which is also derived from plants and animals. In fact, all animals, plants, fungi, viruses, bacteria, and other organisms need the energy to do all they can.

4. What is the best source of renewable energy?

Other sources of renewable energy are solar energy, wind power, biomass and hydropower. It is called renewable because it is continuous. It is also called another form of energy as these are other forms of renewable energy.

5. What is Gravitational Energy?

Gravity is stored at the height of an object

 e.g. high gravity is stored on heavy and elevated objects. When someone climbs into a cliff and picks up speed, the force of gravity turns to the force of motion. Hydropower is another example of gravity, in which gravity forces water down a propeller to provide electricity.

6. Where Does the Energy Come From?

According to the law of conservation, "Energy is not created, or destroyed, but can be changed from one form to another."

The energy we use is simply the conversion of other species. It has no specific sources. However, most of the energy we have used is the result of the Sun.

Looking at the representation above, it is clear that we need power. We get this energy from eating food, which is also derived from plants and animals. In fact, all animals, plants, fungi, viruses, bacteria, and other organisms need the energy to do all they can.

7. What is the best source of renewable energy?

Other sources of renewable energy are solar energy, wind power, biomass and hydropower. It is called renewable because it is continuous. It is also called another form of energy as these are other forms of renewable energy.

8. Can energy be created or destroyed?
No, energy cannot be created or destroyed. This is the fundamental principle known as the law of conservation of energy. Energy can be converted from one form to another or transferred between objects, but the total amount of energy in a closed system always remains constant. This law is one of the most important principles in physics and applies to all physical processes.
9. How does energy conservation apply in real-world scenarios?
Energy conservation applies in all real-world scenarios, but it's often less obvious due to energy transformations and dissipation. For example, when a ball bounces, it doesn't return to its original height because some kinetic energy is converted to heat and sound energy during the collision. In a car engine, chemical energy from fuel is converted to mechanical energy to move the car, but much is lost as heat. Understanding these transformations is crucial for designing efficient machines and processes.
10. How does the concept of energy relate to work?
Energy and work are closely related. Work is done when a force acts on an object to cause a displacement. The amount of work done is equal to the change in energy of the system. When work is done on an object, energy is transferred to it, increasing its energy. Conversely, when an object does work on its surroundings, it loses energy.
11. How does energy relate to the concept of work in physics?
Energy and work are closely related concepts in physics. Work is defined as the transfer of energy that occurs when a force acts on an object to cause a displacement. The amount of work done is equal to the change in energy of the system. When positive work is done on an object, its energy increases. Conversely, when an object does positive work on its surroundings, its energy decreases. This relationship is expressed mathematically as W = ΔE, where W is work and ΔE is the change in energy.
12. What is the relationship between force and energy?
Force and energy are related through work. When a force acts on an object and causes it to move, work is done. The work done is equal to the change in the object's energy. Mathematically, work (W) is the product of force (F) and displacement (d) in the direction of the force: W = F * d. This work changes the energy of the object, either by increasing its kinetic energy if the force is in the direction of motion, or by changing its potential energy if the force is against a field like gravity.
13. How does the concept of energy apply to living organisms?
Energy is fundamental to life processes. Living organisms constantly transform and transfer energy to maintain their complex structures and functions. The primary source of energy for most life on Earth is sunlight, captured through photosynthesis and converted into chemical energy in the form of glucose. This energy is then used in cellular respiration to produce ATP, the energy currency of cells. Energy flows through ecosystems in food chains and webs, and the laws of thermodynamics govern biological processes. Understanding energy in biology is crucial for fields like metabolism, ecology, and evolutionary biology.
14. How does energy relate to the stability of atomic nuclei?
The stability of atomic nuclei is directly related to their energy content. Nuclei are held together by the strong nuclear force, which overcomes the electrostatic repulsion between protons. The most stable nuclei have the lowest energy per nucleon (binding energy per nucleon). This explains why very heavy nuclei can undergo fission (splitting) and very light nuclei can undergo fusion (combining), both processes releasing energy. The famous "curve of binding energy" in nuclear physics illustrates this relationship, showing why iron-56 is one of the most stable nuclei. This understanding is fundamental to nuclear physics, astrophysics, and nuclear energy applications.
15. What is the role of energy in wave propagation?
Energy is fundamental to wave propagation. Waves are disturbances that transfer energy through a medium without transferring matter. In mechanical waves (like sound or water waves), energy is transferred through the oscillation of particles in the medium. In electromagnetic waves (like light), energy is carried by oscillating electric and magnetic fields. The energy in a wave is related to its amplitude and frequency. Higher amplitude means more energy, and higher frequency waves generally carry more energy than lower frequency waves of the same amplitude. This understanding is crucial in fields like optics, acoustics, and telecommunications.
16. How does quantum mechanics change our understanding of energy?
Quantum mechanics revolutionizes our understanding of energy at the atomic and subatomic levels. In quantum theory, energy is quantized, meaning it comes in discrete packets or quanta. This leads to phenomena like discrete energy levels in atoms, where electrons can only occupy specific energy states. The famous equation E = hf (where h is Planck's constant and f is frequency) relates the energy of a photon to its frequency, showing the particle-like nature of light. Quantum mechanics also introduces concepts like zero-point energy, suggesting that even at absolute zero temperature, particles have some residual energy. These ideas are fundamental to modern physics and technologies like lasers and quantum computing.
17. What is the connection between energy and Einstein's theory of relativity?
Einstein's theory of relativity fundamentally changed our understanding of energy. The famous equation E = mc² shows that mass and energy are equivalent and can be converted into each other. This implies that even a small amount of mass contains an enormous amount of energy. In special relativity, the total energy of a particle includes both its rest energy (mc²) and its kinetic energy. As an object approaches the speed of light, its energy increases dramatically, approaching infinity, which explains why nothing with mass can reach the speed of light. These concepts are crucial in high-energy physics, nuclear reactions, and our understanding of the universe.
18. What are the main types of energy?
The main types of energy include:
19. How does kinetic energy differ from potential energy?
Kinetic energy is the energy an object possesses due to its motion, while potential energy is stored energy an object has due to its position or configuration. For example, a moving car has kinetic energy, while a book on a high shelf has gravitational potential energy. Kinetic energy depends on mass and velocity, while potential energy depends on the object's position in a field (like gravity) or its internal configuration.
20. How does mass relate to energy?
Mass and energy are fundamentally related through Einstein's famous equation E = mc², where E is energy, m is mass, and c is the speed of light in vacuum. This equation shows that mass and energy are equivalent and can be converted into each other. It implies that even a small amount of mass contains an enormous amount of energy, which is the basis for nuclear reactions and explains why they release so much energy.
21. What is mechanical energy?
Mechanical energy is the sum of kinetic and potential energy in an object or system. It's the energy associated with the motion and position of an object. In a closed system without friction or air resistance, the total mechanical energy remains constant as an object moves, with kinetic and potential energy converting back and forth. For example, a swinging pendulum constantly exchanges kinetic and potential energy while its total mechanical energy remains the same.
22. How does friction affect energy in a system?
Friction typically reduces the mechanical energy in a system by converting it into thermal energy (heat). When objects move against each other, the friction between them causes some of the kinetic energy to be transformed into heat, which is then dissipated into the environment. This is why moving objects eventually slow down and stop unless additional energy is supplied to overcome friction.
23. What is energy in physics?
Energy is the capacity to do work or cause change in a system. It's a fundamental concept in physics that describes the ability to move objects, heat substances, or power processes. Energy can exist in various forms and can be transferred between objects or converted from one form to another, but it cannot be created or destroyed according to the law of conservation of energy.
24. What is the difference between energy and power?
Energy is the capacity to do work, while power is the rate at which work is done or energy is transferred. In other words, energy is a quantity, and power is the rate of using or transferring that energy. For example, a light bulb may use 60 joules of energy per second, which means its power is 60 watts. Power is measured in watts (W), while energy is typically measured in joules (J) or kilowatt-hours (kWh).
25. What is the significance of the unit 'joule' in energy calculations?
The joule (J) is the SI unit of energy, work, and heat. One joule is defined as the amount of work done when a force of one newton causes a displacement of one meter in the direction of the force. The joule is a derived unit, combining the units of force (newton) and distance (meter). Its significance lies in its universality - it can be used to measure all forms of energy, from the kinetic energy of a moving object to the thermal energy in a cup of coffee, allowing for direct comparisons between different energy forms and simplifying energy calculations across various physics domains.
26. How does temperature relate to energy?
Temperature is a measure of the average kinetic energy of particles in a substance. Higher temperature means the particles have more kinetic energy and are moving faster. When we add thermal energy to a substance, its temperature typically increases (except during phase changes). This relationship between temperature and energy is fundamental in thermodynamics and explains phenomena like heat transfer and thermal expansion.
27. What is the difference between heat and temperature?
Heat is a form of energy transfer between objects due to temperature difference, while temperature is a measure of the average kinetic energy of particles in a substance. Heat flows from objects at higher temperatures to those at lower temperatures. Temperature tells us how hot or cold an object is, but it doesn't tell us how much thermal energy it contains. For example, a cup of boiling water has a higher temperature than a swimming pool, but the pool contains much more thermal energy due to its larger mass.
28. What is the significance of activation energy in chemical reactions?
Activation energy is the minimum energy required for a chemical reaction to occur. It represents an energy barrier that reactants must overcome to form products. This concept is crucial in understanding reaction rates and mechanisms. Reactions with lower activation energies occur more readily than those with higher activation energies. Catalysts work by lowering the activation energy of a reaction, allowing it to proceed more quickly without being consumed in the process. Understanding activation energy is essential in fields like chemical kinetics, enzyme catalysis in biochemistry, and the design of industrial chemical processes.
29. What is the significance of Planck's constant in energy calculations?
Planck's constant (h) is a fundamental physical constant that plays a crucial role in quantum mechanics. It relates the energy of a photon to its frequency (E = hf) and appears in many quantum mechanical equations. Planck's constant sets the scale at which quantum effects become important and classical physics breaks down. It's essential in calculations involving atomic and subatomic particles, explaining phenomena like the photoelectric effect and the quantization of angular momentum. Understanding Planck's constant is crucial for fields like quantum physics, spectroscopy, and modern technologies like lasers and semiconductors.
30. What is potential energy, and what factors affect it?
Potential energy is stored energy that an object possesses due to its position or configuration. The main types are:
31. How does the concept of energy apply to chemical reactions?
In chemical reactions, energy plays a crucial role. Chemical energy is stored in the bonds between atoms in molecules. During a reaction, bonds are broken and formed, leading to changes in the total energy of the system. Exothermic reactions release energy to the surroundings, often in the form of heat, while endothermic reactions absorb energy. The energy changes in chemical reactions are governed by the laws of thermodynamics, particularly the first law (conservation of energy) and the second law (entropy increase). Understanding these energy changes is essential in fields like chemistry, biochemistry, and materials science.
32. What is the relationship between energy and momentum?
Energy and momentum are both conserved quantities in physics, but they represent different aspects of motion. While energy relates to the capacity to do work, momentum is a measure of the quantity of motion. For a moving object, kinetic energy is proportional to the square of its velocity (KE = ½mv²), while momentum is directly proportional to velocity (p = mv). In collisions, both energy and momentum must be conserved, but energy can be converted between forms (e.g., from kinetic to thermal), while momentum is always conserved in its original form. This relationship is crucial in understanding particle interactions and in fields like astrophysics and nuclear physics.
33. How does the principle of energy conservation apply to simple machines?
Simple machines, such as levers, pulleys, and inclined planes, don't create or destroy energy but rather redistribute it to make work easier. They operate on the principle of energy conservation. While they can provide a mechanical advantage (increasing the force applied), they do so by trading off against distance. The work done (force × distance) remains the same, but the force required can be reduced by increasing the distance over which it's applied. This is why a longer lever arm makes lifting easier - it increases the distance, reducing the required force, but the total work (energy transferred) remains constant.
34. What is the relationship between energy and entropy?
Energy and entropy are closely related concepts in thermodynamics. While energy is conserved in any process (first law of thermodynamics), entropy, a measure of disorder or randomness, tends to increase in natural processes (second law of thermodynamics). As energy is transformed or transferred, some of it becomes unavailable for useful work, increasing the system's entropy. This relationship explains why perpetual motion machines are impossible and why energy efficiency is crucial in real-world applications. The interplay between energy and entropy is fundamental to understanding heat engines, chemical reactions, and even the evolution of the universe.
35. How does energy storage work in different systems?
Energy storage involves converting energy into a form that can be stored and later converted back to usable energy. Different systems store energy in various ways:
36. What is the role of energy in phase transitions?
Phase transitions, such as melting, boiling, or freezing, involve significant energy changes. During these transitions, energy is absorbed or released while the temperature remains constant. This energy, called latent heat, is used to break or form intermolecular bonds. For example, when ice melts, it absorbs energy to break the bonds holding water molecules in the solid structure, without changing the temperature. Understanding these energy changes is crucial in thermodynamics, materials science, and meteorology, explaining phenomena from the formation of clouds to the design of heat pumps.
37. How does energy relate to the concept of force fields in physics?
Force fields, such as gravitational or electromagnetic fields, are regions where objects experience a force. These fields can be described in terms of potential energy. An object in a field has potential energy due to its position, which can be converted to kinetic energy as the object moves through the field. The concept of a field storing energy is fundamental in modern physics, explaining phenomena from the behavior of charged particles to the propagation of electromagnetic waves. This understanding is crucial in electromagnetism, gravitation, and quantum field theory.
38. How does energy transfer occur in different physical processes?
Energy transfer can occur through various mechanisms:
39. What is the relationship between energy and power in electrical systems?
In electrical systems, energy is the total amount of electrical work done over time, while power is the rate at which this work is done or energy is transferred. Energy is typically measured in joules (J) or kilowatt-hours (kWh), while power is measured in watts (W). The relationship is expressed as: Energy = Power × Time. For example, a 100W light bulb running for 1 hour uses 100 watt-hours (0.1 kWh) of energy. This relationship is crucial in electrical engineering, power distribution, and energy management.
40. How does the concept of energy apply to quantum tunneling?
Quantum tunneling is a phenomenon where particles can pass through a potential energy barrier that they classically shouldn't have enough energy to overcome. This is possible because in quantum mechanics

Also Read

Basics Of Energy And Its Various Forms

02 Jul'25 07:47 PM

Vertical Circular Motion

02 Jul'25 07:29 PM

Work Done By Variable Force

02 Jul'25 07:29 PM

Work Done By A Constant Force

02 Jul'25 05:42 PM

Elastic And Inelastic Collision

02 Jul'25 05:34 PM

Work, Energy and Power - Definition, Examples, Formula, Units, FAQs

02 Jul'25 05:09 PM

Conservation of Mechanical Energy - Definition, Example, Formula, FAQs

02 Jul'25 05:08 PM

Law of Conservation of Energy - A Complete Guide

02 Jul'25 05:01 PM

Unit of Power - Definition, Unit, FAQs

02 Jul'25 04:59 PM

Kinetic and Potential Energy Difference - A Complete Guide

02 Jul'25 04:58 PM

Articles

Questions related to

Have a question related to ?
Can you list all colleges/universities in India that offer B.Tech/B.E. in sustainable energy/renewable energy?

Hello Sukhada,

Here's the list of few colleges offering B.tech/B.E. in sustainableenergy/renewableenergy :

  1. JLU School of Engineering and Technology, Bhopal
  2. RGIPT Amethi - Rajiv Gandhi Institute of Petroleum Technology, Amethi
  3. Sanjay Ghodawat University, Kolhapur
  4. Sarala Birla University, Ranchi
  5. Sharda University,  Greater Noida

For more colleges and more detailed information you may visit career360: https://engineering.careers360.com/colleges/list-of-be-btech-in-renewable-energy-colleges-in-india

Thank you!!

Read Complete Answer
Anushree Thakare 13 June,2025
Renewable Energy engineering colleges

Hello aspirant,

Here below I am providing you with the name of some of the colleges you can look for:

  • The Indian Institute of Technology Bombay
  • The Indian Institute of Technology Delhi
  • National Institute of Technology Kurukshetra
  • Amity University, Noida
  • K. J. Somaiya College of Engineering

Thank you

Hope this information helps you

Read Complete Answer
Sajal Trivedi 05 June,2025
The total energy carried by the light wave when it travels from a rarer to a non reflecting and non absorbing medium 1) increases 2)either increases or decreases depending upon angle of incidence 3) decreases 4)remains same

When light passes from a rarer to a non-reflecting, non-absorbing medium, the energy remains the same because:

  1. No reflection : All light passes through.

  2. No absorption : The medium doesn't take any energy from the light.

Hence, the energy carried by the light wave doesn't change.

Read Complete Answer
Rohan 01 May,2025
i am a bsc physics student . for cuetpg i applied for a paper MTQP10 electrical power and energy engineering. My doubt if i write the exam will i get admission for that course. what is the eligibility criteria for this course

As a B.Sc. Physics student, eligibility for Electrical, Power, and Energy Engineering (MTQP10) through CUET-PG depends on the university.


Key Points:


Most M.Tech programs require a B.E./B.Tech. degree in Electrical or related fields.


Some universities may accept B.Sc. Physics graduates, but additional bridge courses might be required.

Check individual university eligibility criteria before applying.

If your degree isn’t directly eligible, consider applying for M.Sc. or interdisciplinary programs in related fields.

Read Complete Answer
Poral Siddartha (siddu) 02 March,2025
what is the s ope for renewable energy subject and which college in south India this subject is available

Hello Sheela,

Scope of Renewable Energy

Renewable energy has a huge scope due to the increasing demand for sustainable energy sources. Career opportunities are available in:

  • Solar, Wind, Hydropower, and Bioenergy industries
  • Government projects (MNRE, SECI, NTPC, etc.)
  • Research & Development in energy efficiency
  • Companies like Tata Power, Adani Green Energy, Suzlon, and international firms

    Top Colleges in South India Offering Renewable Energy Courses
  1. IIT Madras – M.Tech in Energy Systems
  2. NIT Trichy – M.Tech in Energy Engineering
  3. Amrita Vishwa Vidyapeetham, Coimbatore – B.Tech & M.Tech in Renewable Energy
  4. VIT, Vellore – B.Tech in Energy and Environmental Engineering
  5. University of Petroleum and Energy Studies (UPES), Bengaluru


For more precise details and scope of this subject CLICK HERE .

I hope this answer helps you. If you have more queries then feel free to share your questions with us we will be happy to assist you.

Thank you and wishing you all the best for your bright future.

Read Complete Answer
kumardurgesh1802 27 February,2025
View All
Back to top