Contents
By learning Physics Topics, we can gain a deeper appreciation for the natural world and our place in it.
Definition And Introduction to Transformation of Energy
Energy exists in many different forms. One form of energy can be changed into another form. The change of one form of energy into another form of energy is known as transformation of energy. We will now take some examples to show how the transformation of energy takes place. Suppose a stone is lying on the roof of a house.
In this position, all the energy of the stone is in the form of potential energy. When the stone is dropped from the roof, it starts moving downwards towards the ground and the potential energy of stone starts changing into kinetic energy. As the stone continues falling downwards, its potential energy goes on decreasing (because its height goes on decreasing) but its kinetic energy goes on increasing (because its velocity goes on increasing).
In other words, the potential energy of the stone gradually gets transformed into kinetic energy. And by the time stone reaches the ground, its potential energy becomes zero and entire energy will be in the form of kinetic energy. From this we conclude that when a body is released from a height then the potential energy of the body is gradually transformed (or changed) into kinetic energy.
The reverse happens when a piece of stone is thrown upwards. When we throw a piece of stone upwards, the initial kinetic energy of the stone starts changing into potential energy. As the stone moves up, its kinetic energy goes on decreasing (because its velocity goes on decreasing) but its potential energy goes on increasing (because its height goes on increasing).
In other words, the kinetic energy of stone gradually gets transformed into potential energy. And when the stone reaches at the highest point of its path, its kinetic energy becomes zero and its potential energy becomes maximum. Thus, at the highest point, the total energy of the stone will be in the form of potential energy. From this we conclude that when a body is thrown upwards, the kinetic energy of body is gradually transformed (or changed) into potential energy.
Energy Transformations at a Hydroelectric Power House
We will now describe the energy transformations which take place at a hydroelectric power house. At a hydroelectric power house, a dam is built on a river. The river water collects behind the dam to form a ‘reservoir’ (see Figure).
Water stored behind the dam has a lot of potential energy but as such this potential energy is of no use to us. If, however, this water is allowed to fall from its great height, the potential energy of water changes into kinetic energy.
This kinetic energy of the falling water is used to drive huge water-wheels or turbines which are connected to electricity generators for producing electricity. Thus, at a hydroelectric power house, the potential energy of water is transformed into kinetic energy and then into electrical energy. The transformations of energy taking place at a hydroelectric power house can be written as :
Potential energy → Kinetic energy → Electrical energy
Energy Transformations at a Thermal Power House
At a thermal power house, coal is used to produce electricity. When coal is burnt, the chemical energy of coal is changed into heat energy. This heat energy converts water into steam. The high pressure steam turns the steam turbines changing the heat energy into kinetic energy.
The turbines run electricity generators which convert kinetic energy into electrical energy. Thus, at a thermal power house, chemical energy of coal is changed into heat energy, which is further converted into kinetic energy and electrical energy.
This can be written as :
Chemical energy → Kinetic energy → Electrical energy
From the above discussion we conclude that one of the important characteristics of energy is that it can be transformed (or changed) from one form to another. We will now discuss some of the important transformations of energy and the appliances which bring about these transformations. Please note that the appliances (machines or devices) which bring about the transformation of energy are called ‘energy converters’.
Using Energy Converters
Energy is like money, it is useful because it can be changed into so many different forms. In our everyday life we make use of many appliances (or machines) which convert (or transform) one form of energy into another form. Some examples of the energy converters which make our life more comfortable are : Electric motor, Electric generator, Electric iron, Electric bulb, Radio, Steam engine, Car engine, Cell (or Battery), Gas stove, Solar water heater and Solar cell. These are discussed below.
1. Electric Motor :
Electric energy spins the motor in various electrical appliances which do various types of work for us. For example, electric energy spins the motor in a fan, causing the fan to turn and cool our room. A motor converts electrical energy into mechanical energy. That is :
Electrical energy → Mechanical energy
Electric motor is used in electric fans, washing machines, refrigerators, mixer and grinder, hair dryer, and many other appliances. A generator is the reverse case of an electric motor. A generator converts mechanical energy into electrical energy.
2. Electric Iron :
When we switch on an electric iron, it becomes hot. So, an electric iron converts electrical energy into heat energy. That is :
Electrical energy → Heat energy
An electric heater also converts electrical energy mainly into heat energy.
3. Electric Bulb :
An electric bulb (or electric lamp) converts electrical energy into light energy. This happens as follows : Electrical energy causes the filament in the bulb to become white-hot and give out light. So, in an electric bulb, electrical energy is first converted into heat energy and then into light energy. The energy transformations taking place in an electric bulb can be written as follows :
Electrical energy → Heat energy → Light energy
Please note that it is not always possible to convert the whole of one kind of energy to any other kind. Usually, one kind of energy gets converted into many kinds of energy. For example, an electric bulb (or lamp) converts electrical energy into light energy but at the same time a lot of heat energy is also produced (which does not get converted to light energy and goes waste).
4. Radio :
A radio converts electrical energy into sound energy. This happens as follows : In a radio set, electrical energy causes the diaphragm in the speaker to vibrate and produce sound. So, a radio first converts electrical energy into kinetic energy and then into sound energy. The energy transformations taking place in a radio set can be written as :
Electrical energy → Kinetic energy → Sound energy
5. Steam Engine :
In a steam engine, heat is used to boil water and obtain steam under high pressure to turn the shaft and drive the wheels. So, a steam engine converts heat energy into kinetic energy (or mechanical energy). That is :
Heat energy → Kinetic energy (or Mechanical energy)
6. Car Engine :
A car burns fuel (like petrol) to get energy and drive its engine. This happens as follows : The car engine converts the chemical energy of petrol into heat energy and then into kinetic energy (or mechanical energy). The transformations of energy taking place in a car engine can be written as :
Chemical energy → Heat energy → Kinetic energy (or Mechanical energy)
7. Cell (or Battery) :
A cell (or battery) contains chemicals and supplies electrical energy required to run various types of appliances. So, a cell (or battery) converts chemical energy into electrical energy. That is :
Chemical energy → Electrical energy
8. Gas Stove :
When cooking gas (LPG) is burnt in a gas stove, then mainly heat energy is produced. So, a gas stove converts the chemical energy of cooking gas into heat energy. That is :
Chemical energy → Heat energy
Please note that during the burning of cooking gas in a gas stove some light energy is also produced.
9. Solar Water Heater :
A solar water heater traps sun’s light and produces heat. So, a solar water heater converts light energy into heat energy. That is :
Light energy → Heat, energy
10. Solar Cell :
A solar cell traps sun’s light and produces electricity. So, a solar cell converts light energy into electrical energy. That is :
Light energy → Electrical energy