Last seen: Sep 30, 2021
(i) Most of the heat produced by burning the fuels in traditional chulhas is lost to the surroundings, only 8% of the heat is utilized in cooking food...
(i) To burn the dry bio-mass, like cattle dung, directly to produce heat. (ii) To convert the bio-mass into more useful fuels and then use these fue...
Photosynthesis.
Advantages (i) The use of water energy does not cause any pollution. (ii) It is a cheap and renewable source of electricity, which will never get ...
The energy of flowing water is an indirect source of solar energy. The heat of solar energy evaporates water from the oceans and the surface of earth....
The minimum wind velocity required for obtaining useful energy is 15 km/h.
When the blowing wind strikes across the blades of wind-mill, it exerts a force on them due to which the blades of the wind-mill start rotating. As lo...
The electricity generated by solar cell panels during the day is stored by using it to charge storage batteries. These storage batteries give us direc...
Solar cells are made from semiconductor materials like silicon and gallium.
The surface is not visible since the radiation incident is more than visible range, i.e., the incident radiation is an infrared radiation which is inv...
(i) Solar energy is used for drying clothes. (ii) Solar energy is used for the preservation of fruits, vegetables and fish, etc., by the process of ...
Infrared radiation.
Ultraviolet rays and infrared rays.
Infrared rays carries the sensation of heat in sunlight.
The wavelength range for the visible radiation is 400 nm in violet to 700 nm in red.
One hour = 60 × 60 = 3600 s Solar constant = 1.4 kW/m2 = 1.4 kJ/s/m2 i.e., in 1s, 1m2 area receives energy = 1.4 kJ So, in 1 hour, i.e., in 3600...
Wood produces a lot of smoke on burning and pollutes the air. Hence it is advised not to use it as a fuel.
(i) Solar energy (ii) Wind energy.
Fossil fuels are present in limited amounts in the earth and they cannot be replaced quickly when exhausted. Hence they are called non-renewable sourc...
Electrical energy is used for lighting bulbs, tubes and to run household appliances. Heat energy obtained by burning wood, coal, kerosene or cooking g...