Name the source of energy in sun and stars.
What are the characteristics of a good source of energy?
Characteristics of a good sources of energy are:
(i) it should give an adequate amount of net energy or work per unit volume or mass,
(ii) it must be convenient to use so as to give energy at a steady rate,
(iii) it must be easy to store and transport,
(iv) it must be economical, and
v) it must be easily accessible.
The raw materials that provide the requisite amount of energy to perform various functions of life are called sources of energy.
For example:
(i) We need heat energy to cook food.
The various sources are: Fuels, wood, coal, kerosene, cooking gas etc.
(ii) We need energy for our transport.
The various sources are: Petrol, diesel.
(iii) We need energy to light bulbs, tubes, to run radio, television and other power appliances.
The source is electricity.
(iv) Production in factories and agriculture also need energy.
The source is diesel and electricity.
List any four sources of energy which are selected for use for a given activity.
1. Energy to run a cycle
2. Energy to run a car
3. Energy to cook food
4. Energy to work on
Four sources of energy used in the activity is:
1. Energy of muscles
2. Chemical energy of petrol or diesel
3. Chemical energy of gas or kerosene
4. Electrical energy obtained from potential energy. Electrical appliances of water, chemical energy of fuels etc.