Class 10 - Physics - Sources of Energy


  1. A solar water heater cannot be used to get hot water on

(a) A sunny day. (b) A cloudy day. (c) A hot day. (d) A windy day.


Correct option: - (b) a cloudy day.

 A solar water heater uses solar energy to heat water. On a cloudy day, the sunlight does not reach the ground. Therefore solar energy is not available for the solar heater to work properly.


Which of the following is not an example of a bio-mass energy source?

(a) wood (b) gobar-gas (c) nuclear energy (d) coal


Correct option: - (c) nuclear energy.

Bio-mass is a source of energy which is obtained from plant materials and animal wastes. Nuclear energy is released by nuclear fission and fusion reaction.

Wood is a plant material, gobar gas is formed from animal dung and coal is a fossil fuel obtained from buried remains of plants and animals.

 Question 3.

Most of the sources of energy we use represent stored solar energy. Which of the following is not ultimately derived from the Sun’s energy?

(a) geothermal energy (b) wind energy (c) nuclear energy (d) bio-mass.


Correct option: - (c) nuclear energy

Nuclear energy is released during nuclear fission and fusion. It is derived from Sun’s energy. But geothermal, wind energy and bio-mass they are the sources of energy which are derived either directly or indirectly from the sun’s energy.

Question 4.

Compare and contrast fossil fuels and the Sun as direct sources of energy.


Fossil fuels and sources of energy from the sun both are natural sources.

Physics Class 10 Energy Comparison between Fossil Fuel & Sun

Question 5.

Compare and contrast bio-mass and hydroelectricity as sources of energy.


Contrast between bio-gas and hydroelectricity are as follows:-

Bio-mass and hydroelectricity both are non-conventional sources of energy.

Working cost of both sources is very low.

Physics Class 10 Energy Sources of Energy

Question 6.

What are the limitations of extracting energy from —?

(a) The wind? (b) Waves? (c) Tides?


  • Limitations of extracting energy from wind:-
    1. It is not available all the time.
    2. Large area is required.
  • Initial establishment cost is high.
  1. Specific locations needed where wind blows mostly & with high speed.

 Limitations of extracting energy from waves:-

    1. Wave energy can be used to harness only when it is due to very strong waves.
    2. Also the devices required to trap wave energy are very costly.

 Limitations of extracting energy from tides:-

    1. Initial set up cost is very high.
    2. Damage to ecosystem.
  • Tides occur only twice a day, so power generation happens only during certain times of a day.



On what basis would you classify energy sources as:-

(a) Renewable and non-renewable?

(b) Exhaustible and inexhaustible?

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


Options (a) and (b) are same.

  • Energy sources which are available in nature and which can be used again and again. Their supply is not affected by the rate at which they are consumed these sources are known as renewable sources.

For example: - Solar, bio-mass, ocean, geothermal and hydro energy sources.

Sources which are not replenished after their consumption and their stock are limited are known as non-renewable sources of energy.

For example: - Fossil fuels (coal, petrol, natural gas, etc.)

  • Sources of energy which run out of stock after using them over a period of time are called exhaustible. Even after using the energy repeatedly from the source if they are available, they are called inexhaustible. Almost all inexhaustible sources of energy are renewable and exhaustible sources are non-renewable.


Question 8.

What are the qualities of an ideal source of energy?


The qualities of an ideal source of energy are as follows:-

  1. It must be economical.
  2. It should be easily available.
  3. It should not emit harmful or greenhouse gases.
  4. It should not leave behind any residue like ash after being used.
  5. It should provide adequate amount of energy.


Question 9.

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


Advantages of a Solar Cooker:-

  1. It saves fuel.
  2. It does not cause pollution.
  3. Easy to install.
  4. It is free from all and available in unlimited amount.

Disadvantages of a Solar Cooker:-

  1. It can be used only on a sunny day.
  2. On a cloudy day, it won’t work.
  3. They are very costly.

Physics Class 10 Energy Solar Cooker

Question 10.

What are the environmental consequences of the increasing demand for energy?

What steps would you suggest to reduce energy consumption?


A few environmental consequences are following:-

  1. More and more greenhouse gases are added to environment leading to global warming.
  2. Glaciers and polar ice caps have started melting.
  3. Depletion of ozone layer.
  4. Air and water pollution.

Steps that can be taken to reduce energy consumption are following:-

  1. Use of electricity and electrical appliances and air conditioners must be reduced.
  2. Public transport should be chosen over individual vehicles.
  3. Prevent unnecessary wastage of water.
  4. Use of solar-cookers, solar-water heaters etc.
  5. Use of cycles should be promoted.



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