Chapter 14 of NCERT Class 10 Science is Sources of Energy. In this chapter you are going to learn about different forms of energy. Chapter 14 of NCERT Class 10 Science has 10 questions in its exercise. These exercises are going to help you with the understanding of basic concepts of both conventional and non-conventional sources of energy.
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NCERT Solution for Class 10 Science Chapter 14 Sources of Energy PDF
What is a good source of energy?
(a) It should be easy to store and transport.
(b) It should not cause pollution.
(c) It should be cheaper.
(d) It should be easily available.
What is a good fuel?
(a) It has a high calorific value.
(b) It is easy to store and transport and easy to access.
(c) Has proper ignition temperature.
(e) Produce less amount of smoke.
If you could use any source of energy for heating your food, which one
would you use and why?
We use Natural gas for heating our food because it is easily available, easy to store and transport, heats food quickly and has proper ignition temperature.
Exercise No: 14.2
What are the disadvantages of fossil fuels?
(i)The disadvantages of fossil fuels are –
(ii)They produce harmful gases which cause air pollution.
(iii)They are non-renewable.
(iv) They produce carbon dioxide which causes global warming.
Why are we looking at alternate sources of energy?
Conventional sources of energy like fossil fuels are non-renewable and are used rapidly. Our energy requirements are increasing as we are consuming more and more so we need to find alternating sources of energy.
How has the traditional use of wind and water energy been modified for
Earlier, wind energy is used through windmills to do mechanical work like lifting water from well. Now the traditional use of wind energy is modified. Wind power generators are used to produce electricity. Traditionally, we used waterfalls as a source of water energy but they are less in number so
we have built dams that store the water. Hydroelectric power generators are used to harness the potential of stored water.
Exercise No: 14.3
What kind of mirror − concave, convex or plain − would be best suited for
use in a solar cooker? Why?
A concave mirror will reflect and focus sunlight at a point. This increases the temperature and cooking takes place.
What are the limitations of the energy that can be obtained from the
Limitations of energy obtained from oceans are –
(i) The maintenance cost of power plants is high.
(ii) Strong waves are required all the time.
(iii) The difference between surface hot water and cold water at depth must be 20 degrees C or more for harnessing ocean thermal energy.
What is geothermal energy?
Geo means earth and thermal means heat, hence heat of earth is used to generate electricity. Due to geological changes, molten rocks which is formed in the deeper hot regions of the crust of Earth are pushed upward and will get trapped in certain regions. This trapped hot region is called hot springs. The stream that is trapped in rocks is routed through a pipe to a
turbine and is used to generate electricity.
What are the advantages of nuclear energy?
(i) High efficiency, produce a large amount of energy by a small amount of fuel.
(ii) It is clean energy, does not produce smoke.
(iii) It produces energy for 2 to 3 years continuously.
Exercise No: 14.4
Can any source of energy be pollution-free? Why or why not?
No source of energy can be pollution-free. Exploiting any source of energy disturbs the environment in some way or another.
Hydrogen has been used as a rocket fuel. Would you consider it a cleaner
fuel than CNG? Why or why not?
When CNG is burnt it produces carbon dioxide as a by-product which causes air pollution while hydrogen produces water as by product. So hydrogen is cleaner fuel than CNG.
Exercise No: 14.5
Name two energy sources that you would consider to be renewable. Give
reasons for your choices.
Wind energy – winds are produced due to uneven heating of the earth and this process is never going to stop. So harnessing windmills used for generating electrical power.
Solar energy– energy obtained from the sun is called solar energy. The fusion of hydrogen into helium produces solar energy. Sun will continue to radiate this energy for a very long time and can be considered as renewable energy.
Give the names of two energy sources that you would consider to be
exhaustible. Give reasons for your choices.
Petroleum – they are made by decomposition of plants and animals under high temperature and pressure, over millions of years. The rate of use is higher than production so they are considered exhaustible.
Wood – it is obtained from forests. The rate of deforestation is increasing due to high demand. Hence, they are considered exhaustible.
Exercise Chapter 14
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
(b)A cloudy day
Which of the following is not an example of a bio-mass energy source?
(b) Goober gas
(c) Nuclear energy
(c) Nuclear energy
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
(c) Nuclear energy
Compare and contrast fossil fuels and the Sun as direct sources of energy.
Similarities-Both are direct sources of energy.
Both are traditional forms of energy.
Differences-Solar energy is a renewable source of energy while fossil fuel is a non-renewable source of energy.
Solar energy does not cause pollution while fossil fuel does.
Solar energy can only be used during the day but fossil fuel can be used anytime.
Compare and contrast bio-mass and hydroelectricity as sources of energy.
Similarities-Both are renewable sources of energy.
Both are traditional form of energy.
Differences-Bio-mass causes pollution while hydroelectricity does not.
Bio-mass energy produced can be used for cooking and heating only but hydroelectric energy can be used for all electric appliances.
Bio-mass energy has low maintenance and can be established easily while special establishment like hydro-power plant is required for hydroelectricity.
What are the limitations of extracting energy from −
(a) the wind? (b) Waves? (c) Tides?
(i) The cost of setting up windmills is very high.
(ii) A large amount of area required for setting up.
(iii) Strong wind waves are required.
(i) Strong ocean waves are required all the time.
(ii) The initial setup cost is high.
(iii) Since waves are erratic, the energy produced from wave energy is unpredictable. Hence not a reliable source of energy.
(i) The cost of maintaining the dam is high.
(ii) High tides required extracting energy but tides depend on the position of Sun, Moon, and Earth.
(iii) The rise and fall of sea-water during high and low tides is not enough to generate electricity on a large scale.
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?
(a) The source of energy that can replenish, that they will occur in nature again is known as renewable energy resources, while the resources that cannot replenish are known as nonrenewable resources.
(b) Exhaustible sources are those sources of energy which can get exhausted from Earth after some time while inexhaustible sources of energy will not get exhausted from nature.
Yes (a) and (b) are the same.
What are the qualities of an ideal source of energy?
Qualities of an ideal source of energy are-
(a) Cheap and easily available.
(b) High calorific value.
(c) It does not produce smoke.
(d) Easy to store and transport.
(e) Safe and easy to handle.
(f) It would do a large amount of work per unit mass.
What are the advantages and disadvantages of using a solar cooker? Are
there places where solar cookers would have limited utility?
(a) Food is cooked at a lower temperature in a solar cooker, hence nutrients are not destroyed.
(b) It does not pollute the environment.
(c) It helps us save fossil fuels.
(a) It can only be used during day time.
(b) It cannot be used during the day if the sun is covered with clouds.
(c) The direction of the panel should be changed according to the sun.
Places where very little sunlight is or have mostly rainy or winter season have limited utility of solar cooker.
What are the environmental consequences of the increasing demand for
energy? What steps would you suggest to reduce energy consumption?
Environmental consequences of increasing demand for energy are-
(i) Rapid consumption of non-renewable sources.
(ii) By-products of burning fossil fuels lead to environmental pollution.
(iii) The establishment of hydro-power plants leads to loss of habitat of aquatic life.
(iv) Deforestation leading to soil erosion.
Steps to reduce energy consumption-
(i) Use of electricity only when needed.
(ii) Use of public transport or bicycles.
(iii) Installation of solar panels for power saving.
(iv) Use of solar cookers.