Std 8 SOURCES OF ENERGY
SOURCES OF ENERGY 10 SOURCES OF ENERGY points to remember : 1. Energy : Energy is needed to do work. Electrical energy, light, sound, heat, gravitational energy, atomic energy, etc., are different forms of energy. It can be converted from one form into another. 2. Fuel : A substance that produces energy on burning is called a fuel. Lakhs of years ago, remnants of plants and animals got buried into the earth and were converted into fossil fuels due to the tremendous pressure of the earth’s layers above them and the heat inside. Coal, mineral oil and natural gas are fossil fuels. Their deposits are limited. 3. Sun : The sun is the only source of energy in the solar system. The energy that we need over one year is provided by the sun in just 40 minutes. Solar heaters and solar cookers can be used to heat water and cook food. In a solar cell, solar energy is converted into electrical energy. 4. Conventional and non-conventional sources of energy : Co...