AN INTRODUCTION TO ENERGY

            We are going to discuss the basics of energy as an introduction to energy in scientific view.

            First of all we will answer the question 'What is energy?' by defining the term "Energy".

            In simple words "Energy of a body is its ability to do work" or "A body possesses energy if it is capable to do work".

Note: Energy is a scalar quantity i.e. it doesn't possess any direction. Energy is measured in joules (J).

Need of Energy:

            A question arises here "Why do we need energy?". The answer is that we need energy to do our routine works. We need energy to walk, we need energy to speak, we need energy to write, even we need energy in every task and we get this energy from the food we eat. Everything, either living or non-living demands energy to perform its functions.

Forms of Energy:

            We can find the energy in  many different forms. "The total amount of energy existing in the word can not be changed" which is called the Law of Conservation of Energy. It can also be described in other words as "Energy can not be destroyed or created, but it can be converted from one form to another".

            Here are Some Major Forms of Energy:

  • Mechanical Energy is the energy present in an object due to its motion of position. e.g. energy stored in running water or energy stored in stretched bow is mechanical energy. It further has two types: Kinetic Energy (related to motion) and Potential Energy (related to position).

  • Heat Energy is the energy coming out from hot bodies. e.g. energy coming out of fire.
  • Light Energy is an important form of energy which is used to see objects around us. e.g. energy coming out of sun and light bulbs.
  • Electrical Energy is the energy which is obtained from moving charges. e.g. energy obtained from cell and electric generator.
  • Chemical Energy is the energy stored in chemical compounds. e.g. energy stored in coal and petrol.
  • Sound Energy is the energy produced due to vibration of an object. e.g. energy produced by vibrating drum.

            We get energy from different sources. Different sources give different forms of energy. For example, We get light and heat energy from sun. We get chemical energy from fossil fuels. We get mechanical energy from water and wind. We get nuclear energy from nuclear fuel.

            One may question "What is the origin of all the energy on our earth?".

Among all the above discussed sources, Sun is the biggest source of energy. The sunlight coming from sun contains heat energy and light energy. These two energies coming from sun are the origin of all the energy present in our earth.

            The energy sources can be divided into two main streams.

  • Renewable Energy Sources are the sources that produce energy in permanent way. For example, sun, water and wind provide energy in permanent way. We mostly use these types of energy indirectly by generating electricity. Therefore, the energy coming from the sun is used directly on a big scale. Non-renewable sources provide us the environment friendly energy which do not pollute our environment in any way. These sources are very cheap. The indirect use of solar energy has been modified in a very useful manner. Man has made solar cells that directly convert solar energy into electrical energy. Solar cells are combined to form a solar panel which give sufficient amount of energy to fulfill our energy demands.

  • Non-renewable Energy Sources are the sources that provide us energy only single time and we can not recycle them to obtain energy in a permanent way. For example, energy obtained from fossil fuels and nuclear fuels. These type of energy sources take millions of years for their formation that is why they are called non-renewable energy sources. Moreover, these sources are not environment friendly. They cause pollution very intensively. When we burn fossil fuels ( oil, gas, coal), they produce harmful carbon dioxide and carbon mono oxide gases. These gases entering in atmosphere cause air pollution and result in different types of diseases like lungs problem, headache and itching of eyes. Nuclear fuel produce a radioactive waste material which can harm the living thing severely. So, the use of these energy sources should be wisely.

Einstein's Mass-Energy Equation:

            Einstein predicted that mass can also be converted directly into energy. This happens in nuclear reaction or when we burn something. According to him

E=mc2

Here, E is energy obtained from m mass and c is the speed of light whose value is 3x108ms-1

This equation shoes that a huge amount of energy can be obtained from a small amount of mass.

            Ultimately, we can say that energy is the basic component of our universe and we get it in different ways. Some of them are harmful and some are safe and cost free. It depends upon us that what do we choose to use.