explain the conservation of principal energy
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The principle of conservation of energy states that energy cannot be created or destroyed, i.e. in an isolated system, the total energy before transformation is equal to the total energy transformation. A few examples of energy transformation are given below:
1. In an electric bulb, electrical energy is converted into light and heat energy.
2. In a microphone, sound energy is converted into electrical energy, while in a loudspeaker electrical energy is converted into sound energy.
3. In a hydroelectric plant,, water falls from a height on to a turbine causing it to turn. The turbine turns a coil in a magnetic field, thereby generating a electric current. Therefore, potential energy of the water is converted into kinetic energy of the turbine, which is converted into electrical energy.
4. In a cell, e.g. a Leclanche cell, chemical energy is converted into electrical energy. If the cell is used to light a bulb, then the electrical energy is converted into light energy.
5. In the sun, nuclear energy is converted into light and heat energy. The same occurs in all nuclear reactions in stars.
6. When a substance is heated, heat energy is converted into kinetic energy of the molecules. Part of the energy is used to do work during expansion.
7. If a tungsten filament is heated, it emits electrons. Thus, heat energy is converted into electrical energy. The effect is called thermionic emission.
8. When a current passes through a resistance, heat is generated. Thus, electrical energy is converted into heat energy, e.g. toasters, irons, geysers, etc.
9. In a bicycle pump, mechanical energy is converted into heat energy. Thus the pump gets hot. Of a gas is compressed, the mechanical work done gets converted into heat energy. Alternatively, is a gas is allowed to expand, it does work and its temperature falls as its energy is used up. If we rub our hands, heat is produced due to friction.
1. In an electric bulb, electrical energy is converted into light and heat energy.
2. In a microphone, sound energy is converted into electrical energy, while in a loudspeaker electrical energy is converted into sound energy.
3. In a hydroelectric plant,, water falls from a height on to a turbine causing it to turn. The turbine turns a coil in a magnetic field, thereby generating a electric current. Therefore, potential energy of the water is converted into kinetic energy of the turbine, which is converted into electrical energy.
4. In a cell, e.g. a Leclanche cell, chemical energy is converted into electrical energy. If the cell is used to light a bulb, then the electrical energy is converted into light energy.
5. In the sun, nuclear energy is converted into light and heat energy. The same occurs in all nuclear reactions in stars.
6. When a substance is heated, heat energy is converted into kinetic energy of the molecules. Part of the energy is used to do work during expansion.
7. If a tungsten filament is heated, it emits electrons. Thus, heat energy is converted into electrical energy. The effect is called thermionic emission.
8. When a current passes through a resistance, heat is generated. Thus, electrical energy is converted into heat energy, e.g. toasters, irons, geysers, etc.
9. In a bicycle pump, mechanical energy is converted into heat energy. Thus the pump gets hot. Of a gas is compressed, the mechanical work done gets converted into heat energy. Alternatively, is a gas is allowed to expand, it does work and its temperature falls as its energy is used up. If we rub our hands, heat is produced due to friction.
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