Energy is defined as the capacity of doing work. Energy comes in different forms - heat (thermal), light (radiant), mechanical, electrical, chemical, and nuclear energy. The energy of a body due to its position with respect to another body is called its potential energy. It is stated as, E = mgh, where E is the potential energy, m is the mass of the body, g is the acceleration due to gravity and h is the distance through which it has been raised. The energy of a body due to its motion is called its kinetic energy. It is stated as, E = ½ m v sq(2), where E is the kinetic energy, m is the mass of the body and v is its velocity. We can classify energy into high and low grade for practical purposes. High-grade energy like electricity is better used for high grade applications like melting of metals rather than simply heating of water. The energy lost or dissipated is called as low-grade energy. In our day to day work we use terms like thermal energy, mechanical energy, electrical energy, chemical energy, electromagnetic energy, etc. These are useful forms of energy. The origin of these forms may be in potential energy or kinetic energy or both. For example heat (thermal) energy is a form of kinetic energy due to the random motion of the atoms or molecules of solids, liquids or gases. Chemical energy, stored in atoms or molecules, is a form of potential energy. Energy can be converted from one form to another. According to the first law of thermodynamics, in any process of conversion of energy the total quantity of energy does not change. But practical experiences tell us that the useful energy output of an energy converter is always less than its energy input. This is because of some loss of energy during the conversion. The sum of energy loss and useful energy output is equal to energy input. The ratio of useful energy output to energy input is the conversion efficiency. Because of the losses it is always less than 100%. The conversion efficiency, generally expressed as a percentage, is high if the losses are low.. Friday, December 5, 2008
Energy funda
Energy is defined as the capacity of doing work. Energy comes in different forms - heat (thermal), light (radiant), mechanical, electrical, chemical, and nuclear energy. The energy of a body due to its position with respect to another body is called its potential energy. It is stated as, E = mgh, where E is the potential energy, m is the mass of the body, g is the acceleration due to gravity and h is the distance through which it has been raised. The energy of a body due to its motion is called its kinetic energy. It is stated as, E = ½ m v sq(2), where E is the kinetic energy, m is the mass of the body and v is its velocity. We can classify energy into high and low grade for practical purposes. High-grade energy like electricity is better used for high grade applications like melting of metals rather than simply heating of water. The energy lost or dissipated is called as low-grade energy. In our day to day work we use terms like thermal energy, mechanical energy, electrical energy, chemical energy, electromagnetic energy, etc. These are useful forms of energy. The origin of these forms may be in potential energy or kinetic energy or both. For example heat (thermal) energy is a form of kinetic energy due to the random motion of the atoms or molecules of solids, liquids or gases. Chemical energy, stored in atoms or molecules, is a form of potential energy. Energy can be converted from one form to another. According to the first law of thermodynamics, in any process of conversion of energy the total quantity of energy does not change. But practical experiences tell us that the useful energy output of an energy converter is always less than its energy input. This is because of some loss of energy during the conversion. The sum of energy loss and useful energy output is equal to energy input. The ratio of useful energy output to energy input is the conversion efficiency. Because of the losses it is always less than 100%. The conversion efficiency, generally expressed as a percentage, is high if the losses are low.. 
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