Class 10 NCERT Physics Chapter 14: Sources of Energy : Answers (NCERT Answers PDF and Handwritten Answers Included)

Chapter 14: sources of energy

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 Exercise and in-text question answers

 In-text question set 1 (page number 243)

Question 1) what is a good source of energy?
Answer) a good source of energy would be one:
     1) which would do a large amount of work per unit time
     2) be easily accessible
     3) be easy to store and transport
     4) which is economical

Question 2) what is a good fuel?
Answer) a good fuel would be one:
     1) which would produce large amount of heat on burning
     2) which does not produce a lot of smoke
     3) and which is easily available

Question 3) If you could use any source of energy for heating your food, which one would you use and why?
Answer) I would prefer LPG over other sources of energy for heating as it:
     1) produce large amount of heat on burning
     2) produces no smoke
     3) it is easily available and is economical

In-text question set 3 (page number 253)

Question 1) what kind of mirror - concave, convex or plain - would be best suited for use in a solar cooker? Why?
Answer) A concave mirror would be best suited for used in solar cooker. This is because concave mirror converges light rays (here, sunlight) to a smaller area, the convergence of Sunlight would increase the temperature faster and hence would cook the food faster, as compared to plane or convex mirror.

Question 2) what are the limitations of the energy that can be obtained from the oceans?
Answer) the limitations of the energy that can be obtained from the oceans are -
1) the locations (for tidal energy) and strong waves (for wave energy) are limited to a specific area.
2) the efficient commercial exploitation is difficult (that is - it is costly to extract these sources of energy)

Question 3) what is geothermal energy?
Answer) geothermal Energy is a form of heat energy which is formed from molten rocks. With due time and geological changes, molten rocks were formed in the deeper and hot regions of Earth's Crust and post up words and trapped in certain regions called ' hot spots'.
This heat energy is used to generate steam which is used to rotate electric generator

Question 4) what are the advantages of nuclear energy?
Answer) the advantages of nuclear energy are -
1) nuclear energy releases a tremendous amount of energy. For example - fission of one atom of Uranium releases 10 million times the energy produced by the combustion of 1 atom of carbon
2) if a nuclear reactor is design for electric power generation, such nuclear 'fuel' can be part of a self-sustaining fission Chain Reaction that releases energy at a controlled level. This released energy can be used for producing steam which can be converted into 
 
In-text question 4 (page number 253 b)

Question 1)Can any source of energy be pollution free? Why or why not?
Answer) no, any source of energy can't be pollution free. Any source of energy disturbs the environment in some way or the other. When we talk of 'clean' fuel like CNG, it would be more exact to say that the particular fuel is cleaner than the other
  In some cases the actual operation of the device may seem to be pollution free (like solar panels or wind mills) but the Assembly of the device would have cost some environmental damage
For example - solar panels is made up of silicon, silicon has to be mined, refined and then it is extracted. The process of Mining or refining is not at all pollution free.

Question 2) hydrogen has been used as a rocket fuel. Would you consider it a cleaner fuel than CNG? Why or why not?
Answer is yet to be found and written SRY For Delay

In-text question 5 (page number 254)
Question 1) Give two energy sources that you would consider to be renewable. Give Reasons for your choices.
Answer) two energy sources which are renewable are wind energy (which are extracted from wind mills) and solar energy (which are extracted from solar panels). This is because the sources such as wind and sun can be replenishable.

Questions 2) Give the names of two energy sources that you would consider to be exhaustible. Give reasons for your choices.
Answer) two energy sources which are exhaustible are coal and petroleum. This is because they are not replenishable, takes millions of years to form and those conditions under which coal and petroleum are formed can't be made in Laboratories.