Energy is the ability to do work. The amount of energy possessed by a body is equal to the amount of work it can do when its energy is released. Types of energy:
- Mechanical energy
- Heat Energy
- Chemical Energy
- Electrical Energy
- Nuclear Energy
- Solar Energy
- Wind Energy
A simple machine is a device which is used to do work more easily an quickly. A leaver is an example of simple machine. Machine reduces the effort needed to do a perticular job.
Moving air is called wind. Wind possess kinetic energy and this energy of wind is utilized for doing work. Wind mills are example of wind energy.
Heat is the source of mechanical energy. Whenever work is done against friction, mechanical energy is converted into heat. Adevice which is used to convert heat energy into mechanical energy is called as heat eangine. Steam enigne, petrol engine and diesel engine are all examples of heat engines.
Device Based on solar energy
We uses several divices in day to life which are based on solar energy. Some of them are:
- Solar Cooker: A solar cooker is a device which is used to cook food. It is painted all black from inside. It also contain a thick glass cover over the box.
- Solar Heater: A solar heater is a device used to heat water by utilizing the energy radiated by the sun. In solar water heater, sunlight is reflected on to black pipes containing water, with the help of plane mirrors.
- Solar Furnace: In a solar furnace thousands of small plane mirrors are arranged in a curve to form a very big convave reflector. Now, if a furnace is placed at the focus of such bic reflector, then the heat energy of the sun is great enough to melt steel. A temprature of upto 3000° C can be produced in a solar furnace
- Solar Cells: Solar cells are device which convert the sunlight into electrical energy or electricity. Solar cells are made from semiconductor like silicon or germanium.
Law of conservation of energy
The law of conservation of energy states that energy can neither be created nor be destroyed. Energy can only be transfered from one form to another.