Sources of Energy
Multiple Choice Questions
- 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.
- Which country is the leader in harnessing wind energy?
- Which of the following is a renewable source of energy
- Which of the following is not an example of a bio-mass energy source?
(b) gobar gas
(c) nuclear energy
- Which of the following is the ultimate source of energy?
(d) fossil fuel.
- The country of winds is
- The power plant which converts potential energy of falling water into electricity is
(a) Thermal plant
(b) Wind plant
(c) Hydropower plant
(d) Nuclear plant.
- Chief Constituent of natural gas is
Ans. 1. (b), 2. (c), 3. (a), 4. (c), 5. (c). 6. (d), 7. (c), 8. (b).
Fill in the Blanks
- The popular name of biogas is………
- Wood is a fuel. ……….
3………….. is used for making solar cells.
- Bio-gas contains upto 75%………….
- Thermal power plants are set up near………
- Flowing water possesses…..energy.
- In the preparation of bio-gas the starting material is mainly……….
- When wood is burnt in a limited supply of oxygen………………….. a residue.
Ans. 1. Gobar gas, 2. primary, (3) Silicon, 4. methane, 5. coal or oil fields, 6. kinetic, 7. cow-dung, 8. charcoal.
- Hydropower plant works on the basis of gravity of earth.
- Wood is a fossil fuel.
- The hot spots are sources of geothermal energy.
- Ethane is the largest component of bio-gas.
- Wind energy is a non-renewable source of energy.
- 1 atomic mass unit is equivalent to 931 MeV.
Ans. 1. True, 2. False, 3. True, 4. False, 5, False, 6. True.
Match the Columns
Column A Columa ‘B’
- Coal, petroleum etc. (a) solar energy
- A mixture of Methane, (b) exhaustible
CO₂ and H₂S
- Solar heating device. (c) fossil fuel
- Pollution free energy. (d) biogas
- Fossil’s fuel. (e) solar cooker
Ans. 1. (c), 2. (d), 3. (e), 4. (a), 5.→→ (b).
Answer in one Word/Sentence
- Name the process that produces a large amount of energy in the sun.
Ans. Nuclear fusion
- What is a solar cell panel?
Ans. A large number of solar cells are combined in an arrangement called panel that can deliver enough electricity for practical use. solar
- Which source of energy is used by artificial satellites and space probes ?
Ans. cells. Solar
- Why is CNG considered an environment friendly fuel?
Ans. CNG does not produce any pollutant or toxic gases on burning.
- What is the use of residual slurry in a biogas plant?
Ans. It is used as organic manure.
- What kind of mirror is best suited for use in a solar cooker?
Ans. Concave mirror, as it reflects and concentrates solar energy from area to a smaller one.
Very Short Answer Type Questions
- 1. What is a good fuel ?
Ans. A good fuel produces a large amount of heat on burning, does not produce lot of smoke and is easily available.
- 2. What kind of mirror-concave, convex or plane-would be best suited for use in a solar cooker? Why ?
Ans. A irror is used in a solar cooker as it uses heat of the sunlight to A concave mirror is cook food. The mirror focuses all the incident sunlight at a point. The temperature at that point increases, thus cooking and heating the food placed at that point.
- 3. What is geothermal energy?
Ans. The thermal energy generated and stored in the earth is called geothermal energy.
- 4. Can any source of energy be pollution free ? Why or why not?
Ans. No source of energy can be pollution free. Every source of energy has some type of pollution. For example, even in nuclear energy, the wastes of nuclear reaction are very dangerous to the environment.
Short Answer Type Questions
- 1. What are the qualities of an ideal source of energy?
Ans. An ideal source of energy has the following characteristics
(i) It produces a lot of heat per unit mass.
(ii) It does a large amount of work per unit volume or mass.
(iii) It is easily accessible.
(iv) It produces less amount of smoke.
(v) It is easy to store and transport.
(vi) It is economical.
- 2. If you could use any source of energy for heating your food, which one would you use and why?
Ans. Natural gas can be used for heating and cooking food because it fulfills all the characteristics of a good fuel. It is a clean source of energy. Although it is highly inflammable, yet it is easy to use and transport. It does not produce of heat on burning large amount of smoke on burning and also produces large amount
- 3. What are the disadvantages of fossil fuels ?
Ans. The disadvantages of fossil fuels are (i) Burning of coal and petroleum causes air pollution as it produces lot of smoke
and other gases.
(ii) Fossil fuels release oxides of carbon, nitrogen, sulphur etc. that cause acid rain, which negatively affects water and soil resources.
(iii) Burning of fossil fuels produce gases such as carbon dioxide that cause green house effect and global warming.
- 4. Why should we look for alternate sources of energy?
Ans. Fossil fuels which are traditionally used by human beings everywhere as energy resources are non-renewable sources of energy. These soures of energy are limited and will be finished after some time. They are being consumed at a large rate. Therefore, we should conserve them and look for alternate sources of energy.
- 5. What are the advantages of nuclear energy?
Ans. The advantages of nuclear energy are as follows
(i) Large amount of energy is produced per unit mass.
(ii) It does not produce smoke and hence is a clean energy.
(iii) Fission of one atom of uranium produces 10 million times energy produced by the combustion of an atom of carbon from coal.
(iv) Fusion of four hydrogen atoms produces large amount of energy, approximately 27 MeV.
- 6. Hydrogen has been used as a rocket fuel. Would you consider it a cleaner fuel than CNG? Why or why not?
Ans. Hydrogen gas is cleaner than CNG. CNG contains hydrocarbons. Therefore, it has carbon content. Carbon is a form of pollutant present in CNG. On the other hand, hydrogen is waste free. The fusion of hydrogen does not produce any waste. Hence, hydrogen is cleaner than CNG..
- 7. Compare and contrast bio-mass and hydro-electricity as sources of energy.
Ans. Bio-mass and hydro-electricity both are renewable sources of energy. Bio-mass is derived from dead plants and animal wastes. Hence, it is naturally replenished. It is a result of natural processes. Wood and gobar gas are examples of bio-mass. Hydro electricity, on the other hand, is obtained from the potential energy stored in water a height. Energy from it can be produced again and again. It is harnessed from water and obtained from mechanical processes.
- 8. What are the advantages and disadvantages of using solar cooker? Are there places where solar cooker would have limited utility ?
Write the advantages of using a solar cooker. (Any three)
Ans. Advantages of using a solar cooker : Solar cooker uses sun’s energy for cooking food. It is inexhaustible and clean renewable source of energy. It is free of cost all and available in unlimited quantity, Hence, operating a solar cooker is not expensive. Disadvantages of using a solar cooker: Cooking with solar cookers requires sunlight, which makes it difficult to use them during winter months or rainy days Cooking also requires a significantly longer time as compared to conventional methods The places where the days are too short or where the clouds cover the sky round the year, there is limited utility for solar cookers.
- 9. Draw a labelled diagram of solar cooker. Ans. Solar cooker :SUN
- 10. Draw a labelled diagram of biogas plant. Ans. Biogas plant:
Long Answer Type/Analytical Questions
- 1. How has the traditional use of wind and water energy been modifed for our convenience ?
Ans. Earlier, windmills were used to harness wind energy to perform mechanical work such as lifting or drawing water from a well. Nowadays, wind mills are used to generate electricity. In windmills, the kinetic energy of wind is harnessed and converted into electricity.
Water energy which was used for transportation earlier, is now a good source to generate electricity. Dams have been constructed on rivers for generating electricity Waterfalls are now used as a source of potential energy which is converted to electrical energy with the help of turbines
- 2. What are the forms and limitations of the energy that can be obtained
from the oceans ?
Ans. The forms of energy that can be obtained from the ocean are tidal
wave energy and ocean energy. The limitations in hamessing these energies are
Tidal energy depends on the relative positioning of the earth, the moon and
(2) High dams are required to be built to convert tidal energy into electricity
(3) The location sites where such dams can be built are limited.
(4) To harness ocean thermal energy, the difference in the temperature of surface
water (hot) and the water at depth (cold) must be 20°C or more.
- 3. Compare and contrast fossil fuels and the sun as direct sources of energy.
Ans. Fossil fuels are the energy sources like coal and petroleum, obtained from
underneath the earth’s crust. They are directly available to human beings for use. Thus,
fossil fuels are the direct source of energy. These have been formed over millions of
years and have limited reserves. They are non-renewable sources of energy because
these cannot be replenished in nature. If the present fossil fuel reserve of the earth gets
exhausted, its formation will take several years. They are also very costly.
Contrary to it, solar energy is a renewable and direct source of energy. Solar energy
is inexhaustible. It is available free of cost and is in unlimited amount. It replenishes
by the sunlight itself.
- 4. What are the environmental consequences of the increasing demand for
energy? What steps would you suggest to reduce energy consumption ?
Ans. Industrialization has increased 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 green house gases in the atmosphere, resulting in global warming and a rise
in the sea level. It is not possible to completely stop the consumption of fossil fuels
However, some measures can be taken such as, using electrical appliances wisely and
not wasting electricity. Water should be conserved and used wisely. 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.