Energy:
Energy is the Capacity to do work. The SI unit of energy is joule.
Work cannot be done without energy. When work is done, energy is used or converted from one from to another. To a scientist, work is any action that uses energy. Scientist talk about two basic types of energy.
Forms of energy:
Besides kinetic energy and potential energy there are many types of energy that surrounds us. There is energy in the wind that blows , there is energy in the water the flows. There is energy in the fuel that burns. Most of the energy can be harnessed for doing useful work.
Some of these forms of energy and their uses are discussed here.
1. Heat energy: When water is boiled, the heat energy changes water into steam. The steam is used to do work such as turn turbines and railway engines.
2. Light energy: Green plants in the presence of sunlight make food. The light energy is used to start chemical reaction within the leaves of the plant. Chemical reactions take place when light falls on photographic plates. Light causes chemical; changes, hence it is a form of energy.
3. Chemical energy: Food made by plants store energy in the form of chemicals. Man and animals use the food to release energy, some of which is stored in our muscles. This stored energy is used for doing work. A piece of coal, log of wood or a drum of oil also contains stored chemical energy. When ignited these can produce energy in the form of heat and often light. The energy of the diesel can be used to drive a truck or train while that of coal and wood can used for cooking food.
4. Sound energy: If you place your finger tips against your throat when you speak or against a ringing alarm clock, you can feel the vibrations or movement produced by the sound. The sound of thunder, airplanes, bombs, crackers also produce vibrations which cause glass panes to rattle. The vibrations occur due to the energy of the sound. Hence, sound is a form of energy.
5. Electrical energy: When you switch on the radio or television, electric current passed into it and produces sound. The set also gets heated up. Electricity can produce heat, light and sound energy. Hence, it is a form of energy.
6. Magnetic energy: Energy is stored in permanent magnet because a magnet can move a piece of iron, thus, doing work on it.
7. Nuclear energy : The heat and light of the sun is produced when hydrogen atoms join together to form helium. The atoms store energy in their nucleus. The nuclear energy released when atoms split up is used in power stations to generate electricity. The nuclear energy is also released during the explosion of an atom bomb.
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