NCERT Class X Science Solutions: Chapter 14 – Sources of Energy Part 2 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Question 6:

What are the limitations of extracting energy from?

  1. The wind?
  2. Waves?
  3. Tides?


  1. Wind energy is harnessed by windmills. One of the limitations of extracting energy from wind is that a windmill requires wind of speed more than 15 km/h to generate electricity. Also, a large number of windmills are required, which covers a huge area. For a 1 MW generator, the farm needs about 2 hectares of land. The initial cost of establishment of the farm is quite high. Moreover, since the tower and blades are exposed to the vagaries of nature like rain, Sun, storm and cyclone, they need a high level of maintenance.
This Image Shows Windmills
  1. Very strong ocean waves are required in order to extract energy from waves.
  2. Very high tides are required in order to extract energy from tides. Tidal energy is harnessed by constructing a dam across a narrow opening to the sea. The locations where such dams can be built are limited.

Question 7:

On what basis would you classify energy sources as?

  1. Renewable and non-renewable?
  2. Exhaustible and inexhaustible?

Are the options given in (a) and (b) the same?


Three methods of producing magnetic field are as follows:

  1. The source of energy that replenishes in nature is known as renewable source of energy. Sun, wind, moving water, bio-mass, etc. are some of the examples of renewable sources of energy.

The source of energy that does not replenish in nature is known as non-renewable source of energy. Coal, petroleum, natural gas, etc. are some of the examples of non - renewable sources of energy.

  1. Exhaustible sources are those sources of energy, which will deplete and exhaust after a few hundred years. Coal, petroleum, etc. are the exhaustible sources of energy.

Inexhaustible resources of energy are those sources, which will not exhaust in future. These are unlimited. Bio-mass is one of the inexhaustible sources of energy.

Yes. The options given in (a) and (b) are the same.

Question 8:

What are the qualities of an ideal source of energy?


An ideal source of energy must be:

  • Economical
  • Easily accessible
  • Smoke/pollution free
  • Easy to store and transport
  • Able to produce huge amount of heat and energy on burning

Question 9:

What are the advantages and disadvantages of using a solar cooker? Are there places where solar cookers would have limited utility?


Solar cooker uses Sun՚s energy to cook food stuff. It is inexhaustible, clean and renewable source of energy. It is free for all and available in unlimited amount. Hence, operating a solar cooker is not expensive.

Disadvantage of a solar cooker is that it (solar cooker) is very expensive. It works only in sunlight. Hence, on cloudy day, it becomes useless.

The places where the days are too short or places with cloud covers round the year, have limited utility for solar cooker.

Question 10:

What are the environmental consequences of the increasing demand for energy? What steps would you suggest to reduce energy consumption?


Industrialization increases the demand for energy. Fossil fuels are easily accessible sources of energy that fulfil this demand. The increased use of fossil fuels has a harsh effect on the environment. Too much exploitation of fossil fuels increases the level of greenhouse gas content in the atmosphere, resulting in global warming and a rise in the sea level.

It is not possible to completely reduce the consumption of fossil fuels. However, some measures can be taken such as using electrical appliances wisely and not wasting electricity. Unnecessary usage of water should be avoided. Public transport system with mass transit must be adopted on a large scale. These small steps may help in reducing the consumption of natural resources and conserving them.

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