Question

10th class ki science Mein chapter number 14 ke upar project file​

Answer 1

(I)THE SUN (SOLAR ENERGY) :

The sun is our main source of energy. Light from the sun is captured by the plants through photosynthesis. The sun's energy is converted into chemical energy & stored in various parts of the plant. In this process carbondioxide and water are converted into carbohydrates. Thus, the source of energy for our food is the sun. The animal cannot make their own food. They depend on plants for the food. The carnivorous animals eat other animals. But, ultimately the primary source of all food is plants.

Sunlight contains infra-red radiations in large proportion and these infra-red rays heat all objects on which they fall. Traditionally solar energy is used for drying clothes, drying fruits and vegetables, reducing moisture content in grains and making salt from sea water. But, not we are trapping solar energy to convert it into thermal & electrical energy. The conversions takes place mainly by solar thermal pathways and through photovoltaic conversions.

Solar energy is used in devices such as :

1. Solar Cookers - for cooking.

2. Solar water heaters - for eating.

3. Solar cells - to produce electricity. It is also used to operate watches, calculators space satellites etc.

4. Solar Dryers - for drying clothes & for drying fruits & vegetables.

5. Solar Energy is also used for community lighting pumping of water for small irrigation and drinking purposes.

(II) WIND (WIND ENERGY) :

Wind energy is the energy possessed by moving air or wind by the virtue of its kinetic energy, due to its motion. Wind power is converted into mechanical and electrical energy. The wind energy can be utilized to :

(i) Sail Boats.

(ii) Flight Gliders.

(iii) Lift Water from the Wells.

(iv) Run Wind Mills.

(v) Produce electricity by using wind turbines in remote areas, where plenty of wind energy is available.

(III) FUELS :

In our day-to-day life the most important energy sources are fuels. Fuels are a concentrated store of energy. Most of the fuels are compounds of carbon. Fuels on burning gives heat and light. The commonly used fuels in our country are coal, petroleum natural gas.

COAL :

Coal is main source of energy. Coal is a complex mixture of compounds of carbon, hydrogen and oxygen and some free carbon. Small amount of nitrogen and sulphur compounds are also present in coal.

It is found in deep coal mines water the surface of earth. Some of the major coal-producing countries of the world are : China, America, England, Germany, Poland, Australia and India. In India coal is mainly found in Bihar, West Bengal, Orissa and Madhya Pradesh. Coal is found in abundance in our country and it is the most important source of energy in our country. Coal provides about 67% of energy needs in our country. Due to this, coal is regarded as the back-bone of the energy sector of our national economy.

BIO GAS :

The remains of plants and animals are mostly made of carbon compounds. Carbon compounds burn to give energy. Wood, agricultural waste and animal dung are used as energy sources. In the absence of air, a suspension of plant and animal material in water decomposes to give methane & carbondioxides. This mixture of gases in known as Biogas. Several lakh bio-gas plants have been setup in India.

Wood, agricultural waste and animal dung cakes are burned in open chulhas. Most of the heat generated by burning these fuels in lost to the environment. Only about 6 percent heat in utilized in cooking. In contrast, a biogas stove is much more efficient. Modern smokeless chulhas have been designed. These burnless fuel & utilize the heat more efficiently. Thus fuel is saved. Better design of energy conversion appliances is a way of saving fuels.

USES OF BIOGAS :

(i) Biogas is an excellent fuel for cooking.

(ii) It can also be used for street lighting and for running engines.

(iii) The slurry residue after removal of biogas is a good source of manure for plants.

ELECTRICITY :

Electricity is another form of energy source. It is used to light our homes. Fans, refrigeratory, air-conditioners and other household appliances own on electricity.

Electricity is generated in a power station. The basic principle is that if a conducting wire is moved in a magnetic field an electric current is generated in the wire. In the power stations, electromagnets attached to a turbine are rotated inside a coil of wire. The energy for the rotation turbine is provided by steam or by flowing water. In a thermal power station, the steam is generated by heating water with fuels such as coal, fuel oil or natural gas. On the other hand, in a hydroelectric power station, the flowing water is made available from a dam.

Electricity in a very convenient sauces of energy. It can be easily transported through wires of copper and aluminium. Electrical energy can be easily converted into mechanical, heat, light or chemical energy.