Last seen: Sep 30, 2021
A resource which can provide adequate amount of energy in a convenient form over a long period of time constitutes a source of energy.
(i) The combustible substance like furniture, clothes and books, etc., are removed first when fire starts in a room, so that the fire may not spread d...
The conditions for combustion to take place are: (i) Presence of a combustible substance. (ii) Presence of a supporter of combustion like air or o...
Calorific value of wood = 15KJ/g Conversely the same energy (15KJ) is required to form 1g of wood. Energy required to form 10Kg of wood = 10 × 100...
Calorific value of wood = 15 kJ/g = 15000 J/g Mass of wood = 1 kg = 1000 g Therefore heat produced by 1 kg of wood = 15000 × 1000 = 15 × 105 J.
Mass of water = 2 kg = 2000 g Specific heat of water = 4.2 J/g °C Rise in temperature, t = 70 ° C – 20 °C = 50°C We know that heat produced Q = ...
Fossil fuels are non-renewable source of energy, because if they are exhausted, it cannot be regenerated in a short time. This is because of the fact ...
(i) The bio-gas obtained from animal dung and bio-wastes can be used as a smokeless fuel. (ii) It gives us a clean fuel. (iii) The spent dung can ...
Two types of biogas plants are being used in our country; they are 1. The fixed-dome type 2. The floating gas-holder type the main raw material us...
Charcoal is a better fuel than wood because of the following reasons: (i) Charcoal has better calorific value than wood, i.e., charcoal produces mor...
Let us take two glass tubes. In one tube we put some small pieces of soft wood and in other tube, we put some water. These two tubes are then arranged...
The energy from oceans is obtained in three forms: (i) Tidal energy (ii) Ocean waves energy and (iii) Ocean thermal energy Ocean thermal energ...
(i) When hydrogen gas is lighted, it burns with an explosion which is very unsafe. (ii) It is very expensive to produce hydrogen gas by the electro...
Wind energy farms can be established over a big area of land, where sufficient wind is blowing always, because electricity generated by a single wind ...
Solar cells are used for street-lighting, for traffic signals, for operating water-pumps and for running radio and television sets in remote areas.
(i) The electricity generated by solar cells during the day is stored by using it to change storage batteries. These storage batteries give us direct ...
Box-type solar heater: In this type of heater, a plane reflector is used which does not concentrate solar energy at a point. It produces comparati...
The heat absorbing property of black surfaces and the green house effect are utilised in making solar cookers. There are various types of solar cooker...
Ultra-violet rays and gamma rays are the components of solar radiation which could a health hazard.
The ultra-violet rays and the gamma rays present in the solar energy is absorbed by the atmosphere as it comes down towards the surface of the earth, ...