Those sources of energy which are being produced continuously in nature and are inexhaustible, are called renewable source of energy. For example, wood is a renewable source of energy because if trees are cut from the forests for obtaining wood, than more trees will grow in the forest i…
The ability to see is called vision. It is also eyesight. Vision is known as 'drishti' in Hindu. Sometimes the eye of a person cannot focus the image of an object on the retina properly. In such cases the vision of a person becomes blurred and he cannot see either the distant o…
Light Is a form of energy. Light is needed to see things around us. We are to able see the beautiful world around us because of light. We can read a book, see pictures in a marazine, and watch television and movies due to the existence of light. And it is light which makes us see our im…
There are advantage of having two eyes instead of one. Some of these are given below: 1. Having Two Eyes Gives a Wider Field of View. A human being has a horizontal field of view of about 150° with one eye open, the field of view becomes 180°. Thus, having two eyes gives a wider field o…
A normal eye can see the distant objects as well as the nearby objt clearly.We will now discuss how the eye is able to focus the objects lying at various distances. An eye 👀 focus the image of the distance objects as well as the nearby objects on its retina by changing the focal length…
' Geo' means 'earth' and 'thermal' means ' heat'. Thus, geothermal energy is the heat energy from hot rocks present inside t earth. This heat can be used as a source of energy to produce electricity. Please note that geothermal is one of t few sources of …
The retina of our eye has a large number of light- sensitive cells. There are two kinds of light- sensitive cells on retina: rods and cones. (1). Rods are the rod- shaped in the retina of an eye which are sensitive to dim light. Rods are the most important for vision in dim light (as du…
The main parts of the human eye are: Cornea, Iris, Pupil, Ciliary muscles, Eye lens, Ratena and Optic nerve. The eye -ball is approximately spherical in shape having a diameter of about 2.5 cm. We will now describe the construction and working of the eye. Construction of the Eye The fro…
The materials which are burnt to. Produce heat energy are known as fuels. Examples of fuels are: wood, Coal, Cooking gas (LPG), Kerosene, Diesel and Petrol. In our day life, the most important source of energy are fuels. Fuels are, in fact, the concentrated store- house of energy. This …
A biogas plant consists of a well shaped, underground tank T called digester, which is made of bricks, and has a dome- shaped roof D, also made of cement and bricks. The disgester is a kind of sealed tank in which there is no air (or oxygen). The dome of the digester tank acts as a gas…
The dead parts of plants and trees, and the waste materials of animals are called biomass. Biomass is called organic matter which is used as a fuel to produce energy. Biomass includes wood, agricultural wastes (crop residues) and cow-dung. Biomass contains chemical energy in the form of…
