According to the basic definition, energy means the ability of a body to do work. Energy is shifted from one place to another, with work. Energy is a scalar quantity which is measured in joules. According to law of conservation of energy, “Energy cannot be created or destroyed, however its form changes. It remains conserved (the total amount of energy does not change) in all phenomena”. There are various types of energy as can be seen below:
When the energy travels from one point to another, then it is known as energy transfer. There are 4 basic ways, by which energy gets transferred.
- By mechanical way
- By electrical way
- By radiations (light and sound waves)
- By heating (conduction, convection and radiation)
Types of energy
Usually, energy is classified into kinetic and potential, and all other types of energy are taken as sub types of kinetic or potential. Here we will discuss all types of energy in detail.
The energy which is required in any kind of motion is known as kinetic energy. It is measured as
K.E = (1 / 2) m v2
Where m is the mass of object and v is the velocity, with which object is moving.
Types of kinetic energy
Radiant energy is a type of electromagnetic energy which is experienced in form of heat. It travels in the form of waves or particles. It can be visible (light) or invisible (radio or x-rays). Sunlight is an example of radian energy.
This term is mostly used in solar energy, heating, radiometry and lighting. As electromagnetic radiations travel as a stream of photons, so in case of radiant energy, it can be considered that the energy is carried by these photons. Like all EM radiation, energy is carried in oscillating electric and magnetic fields of these waves.
Thermal energy which is also termed as heat energy, is produced with the rise of temperature. This rise causes atoms and molecules to move/vibrate faster and collide with each other with enhanced energy.
Thermal energy is also related to the internal energy of system. When external temperature is increased, then their internal energy increases due to the increase in thermal energy (since internal energy is sum of all energies). Due to which molecules vibrate faster.
Unlike light energy, sound energy needs a medium to pass, so sound cannot pass through vacuum. Sound energy travels in the form of waves. Sound energy gets transmitted by solids, liquids and gases. It travels faster through solids as compared to gases, as the atoms in solids are closer to each other.
It is an energy form which humans can hear, but only those sounds are audible to humans which lie in the frequency range of 16 Hz to 20 KHz. When sound is produced through some source, then it produces vibrations in air, just in front of that source, then with the help of air molecules motion, this sound wave gets shifted to another location. This is the way, how sound travels.
This type of energy is caused due to the motion of electric charges like electrons. The electrons will carry more electrical energy, if they move faster. Batteries and cells are the sources of electrical energy.
Electrical energy is considered as a type of potential energy because this energy is stored due to relative positions of charged particles (as charges are static). This energy will no longer remain as electric, if charges start motion, then it will become as magnetic.
It is the energy, which is stored in objects as they move. It is the sum of kinetic and potential energy. More energy will be stored, if objects move faster. For example, when a pendulum is at mean position it only has potential energy.
Now if we displace it to the extreme position, then potential energy will increase.
As we leave pendulum, its potential energy starts decreasing and kinetic energy increases.
Then it continues its to and fro motion. Its energy keeps changing from one form to another but the total mechanical energy is same.
Its other examples include, spring compressing and stretching, hitting a nail with hammer, motion of swing etc.
Light energy is a form of electromagnetic radiation. It consists of photons and travels in form of waves. This is the only type of energy, which is visible to human eye.
It falls in category of kinetic energy, as light is never at rest. Its sources can be lasers, sun, bulbs etc. when an atom is provided by energy, then its electrons move from lower energy level to higher energy level. Since these electrons are not stable in higher level, so they return back, which results the emission of photons. Light has the highest speed n universe, as light photons carry no mass. Speed of light is 3 x 108 m / s.
The energy that an object possesses due to its position is known as potential energy. It is measured as
U = m g h
Where m is mass of object, g is gravitational acceleration and h is the height of object.
Types of potential energy
This energy is associated with gravity. An object at certain height will have more gravitational potential energy as compared to an object, which is at ground level.
Gravitational potential energy means the work done to bring a unit mass from one point to another, against the action of gravity. It is given as
U = – G M m / r
Due to inverse law, the gravitational potential energy becomes zero when r becomes infinity. This negative sign indicates the bound state of objects with each other.
As clear from the name, this energy comes from the nucleus of the atom. This energy gets released during the nuclear fission reaction, when the nuclei split apart.
In a nuclear reactor, when a heavy nucleus breaks, then a huge amount of nuclear energy is produced. The heat that is released by this fission reaction is then used to create steam which spins a turbine to generate electricity.
When an external force produces some deformation in an object, then the energy is stored in that object, which is known as elastic energy. This energy is stored in the bonds, which hold the atoms together. As the external stress is removed, the bonds release that absorbed energy. This factor makes a variety of things elastic.
Definitely, bonds can absorb energy, up to some limited extent. When more stress is applied, then these bonds don’t come back to original shape or even break, when stress is removed. This factor makes them as plastic materials. Elastic potential energy is given by
U = (1 / 2) k x2
Elasticity can also be termed as the reversibility of a material. However, all materials have some degree of distortion which they can endure without breaking.
Chemical energy releases when the chemical reaction takes place. It is stored in the bonds of chemical compounds. Usually, after the release of chemical energy, substance completely transforms into a new substance. Chemical energy may get released during the chemical reaction in the form of heat, such reactions are known as exothermic reactions.
The food that we eat provides us chemical energy, which is then converted to mechanical energy and heat. The chemical energy of a battery or cell is converted into electrical energy.