DIFFERENT SOURCES OF ENERGY
What can then be considered a good source of energy? We, in our daily lives, use energy from various sources for doing work. We use diesel to run our trains. We use electricity to light our street-lamps. Or we use energy in our muscles to cycle to school.
Activity 14.1:
* List four forms of energy that you use from the morning, when you wake up, till you reach school.
* From where do we get these different forms of energy?
* Can we call these ‘sources’ of energy? Why or why not?
The muscular energy for carrying out physical work, electrical energy for running various appliances, chemical energy for cooking food or running a vehicle all come from some source. We need to know how do we select the source needed for obtaining the energy in its usable form.
Activity 14.2:
* Consider the various options we have when we choose a fuel for cooking our food.
* What are the criteria you would consider when trying to categorise something as a good fuel?
* Would your choice be different if you lived
a) in a forest?
b) in a remote mountain village or small island?
c) in New Delhi?
d) lived five centuries ago?
* How are the factors different in each case?
After going through the two activities above, we can see that the particular source of energy, or fuel, we select for performing some work depends on many different factors. For example, while selecting a fuel, we would ask ourselves the following questions.
i. How much heat does it release on burning?
ii. Does it produce a lot of smoke?
iii. Is it easily available?
Can you think of three more relevant questions to ask about fuel?
Given the range of fuels we have today, what are the factors which would limit our choices when it comes to a particular task like cooking our food? Would the fuel selected also depend on the work to be done? For example, would we choose one fuel for cooking and another for heating the room in winter?
We could then say that a good source of energy would be one
* which would do a large amount of work per unit volume or mass,
* be easily accessible,
* be easy to store and transport, and
* perhaps most importantly, be economical
Questions
1. What is a good source of energy?
2. What is a good fuel?
3. If you could use any source of energy for heating your food, which one would you use and why?
Source: This topic is taken from NCERT TEXTBOOK