NCERT Solutions Class 10 Science Chapter 14 Sources of Energy
NCERT Solutions Class 10 Science Chapter 14 Sources of Energy: National Council of Educational Research and Training Class 10 Science Chapter 14 Solutions – Sources of Energy. NCERT Solutions Class 10 Science Chapter 14 PDF Download.
NCERT Solutions Class 10 Science Chapter 14: Overview
Board |
NCERT |
Class |
10 |
Subject |
Science |
Chapter |
14 |
Chapter Name |
Sources of Energy |
Topic |
Exercise Solutions |
NCERT Solutions Class 10 Science Chapter 14 – Sources of Energy
Middle Exercise:
Page 243
1.) What is the good source of energy?
Ans:
The energy source which follows following conditions is the good source of energy:
- The ideal source of energy is that energy source which do large amount of work per unit volume or mass.
- That source must be easily accessible.
- That source must be easy to store and also to transport.
- And most importantly, that source must be economical.
2.) What is good fuel?
Ans:
The good fuel must possess following properties:
- It must have low ignition temperature and produces more heat.
- They are easy to store and may burn easily and fastly.
- They must be inexpensive, easily available and does not emit any smoke after burning.
3.) If you could use any source of energy for heating your food, which one would you use and why?
Ans:
- I would prefer to use solar energy for cooking food which is available in large amount and daily and also free of cost.
- After daily use of solar energy over a large amount then also solar energy doesn’t exhaust. Because, sun is the inexhaustible source of energy.
- And main thing is that, the use of solar energy has no harmful effects on human being and environment also.
- So I will mostly prefer solar energy for cooking food.
Page 248
1.) What are the disadvantages of fossil fuels?
Ans:
- Fossil fuels are the non renewable or exhaustible source of energy which may exhaust after some years.
- And for generating fissile fuels many decades may requires.
- After burning of fossil fuels there is release of many gases which causes global warming and hence creates pollution.
2.) Why are we looking alternative sources of energy?
Ans:
- We are using non renewable sources of energy over a large amount which may exhaust after some years and at that time there will be no energy is available for future generations.
- So to keep energy sources for future generations and also to reduce the pollution due to non renewable sources of energy like fossil fuels we are looking for alternate sources of energy which may renewable energy sources or inexhaustible energy sources which creates no pollution and can be maintained life time.
3.) How has the traditional use of wind and water energy been modified for our convenience?
Ans:
- The wind energy was used for lifting the water from well in farms long years ago.
- And also wind energy is used for grinding wheat into flour. Also wind energy is used for many purposes of agriculture.
- Now a days traditional use of wind energy is modified and it is used to generate electricity on large scale.
- While traditionally, water falls may be used as source of water energy as it falling down with high speed.
Page 253
1.) What kind of mirror – concave, convex or plain would be best for use in solar cooker? Why?
Ans:
- Concave mirror is the best suitable for cooking food in solar cooker.
- Because when solar radiation are incident concave mirror it reflects them and concentrates in a single point due to which at that point large amount of heat is generated and food will be cooked easily.
- Hence, concave mirror are most beneficial for cooking food in solar cookers.
3.) What is geothermal energy?
Ans:
- The geological changes causes the formation of molten rocks inside the earth crust where there is large heat but they get trapped upward in particular regions which are called as hot spots.
- When water from underground comes in contact with these hot spots steam will be created and sometimes such hot water floods out from the land or earth crust which we called as hot springs. And then these steam is used to rotate turbines are thereby produces electricity.
- And this is all about the geothermal energy.
4.) What are the advantages of nuclear energy?
Ans:
- Through the process of nuclear fission the nuclei of heavy atoms are bombarded with low energy neutrons which splits it into lighter nuclei and tremendous amount of energy is released.
- The nuclear reactors are designed such that the nuclear fuel acts as the part of self sustaining fission chain reaction and due to which energy will be released at a constant and controlled rate.
- In this way, the energy released can be used further to generate steam and then electricity.
- Thus we did not need to give further extra energy as it is the fission chain reaction.
Page 253
1.) Can any source of energy be pollution free? Why or why not?
Ans:
- There is no source of energy which is not producing pollution.
- Such as nuclear energy is obtained from unstable nuclei having huge mass. During this fission process many of the nuclear wastes are left which may cause pollution also.
2.) Hydrogen has been used as a rocket fuel. Would you consider it a cleaner fuel than CNG? Why or why not?
Ans:
- Obviously hydrogen is the cleaner fuel than CNG because it does not generate any waste after burning while water is generated after burning of hydrogen. Hence it can not produce any type of pollution.
- But CNG i.e. compressed natural gas contains hydrocarbons due to which after burning of CNG the green house gas like CO2 is emitted. Also, the burning of CNG evolves some gases which may cause pollution and acid rain also.
Page 254
1.) Name two energy sources that you would consider to be renewable. Give reason to your choices.
Ans:
- The energy sources like wind energy, solar energy, biogas are the renewable energy sources as their continuous use also may not exhaust them.
- Also solar energy is the inexhaustible source of energy and available in large amount which is also free of cost. And main thing it doesn’t create any type of pollution also.
2.) Give the names of two energy sources that would be you considered as exhaustible. Give reason for your choices.
Ans:
- The fossil fuels such as coal and petroleum are the exhaustible source of energy.
- Because now a days we are more dependent on the fossil fuel for consumption of energy which may exhaust after some years as these are non renewable energy sources.
- Also for the production of fossil fuels may take many decades. And also burning of fossil fuels creates pollution and more dangerous effects on environment.
- So they are inexhaustible sources to keep them we have to alternate renewable energy sources.
Exercise Solution
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
Ans: b) a cloudy day
Explanation: Because on cloudy there will be no sufficient solar energy is available for producing hot water by using solar water heater.
2.) Which of the following is not an example of a bio mass energy source?
a) wood
b) gobar gas
c) nuclear energy
d) coal
Ans: d) coal
Explanation: Because coal is the fossil fuel
3.) Most of the sources of energy we use represent stored solar energy. Which of the following is not ultimately derived from suns energy?
a) geothermal energy
b) wind energy
c) nuclear energy
d) biomass
Ans: c) nuclear
Explanation: Because nuclear energy is totally independent on the solar energy as it is formed due to the fission of unstable heavy nuclei by bombarding low energy neutrons on them.
4.) Compare and contrast fossil fuels and the sun as direct sources of energy.
Ans:
Fossil fuels:
- The fossil fuels which are coal and petroleum were formed over millions of years ago and these sources are only in limited reserves. And hence these sources direct sources of energy and they are non-renewable sources of energy.
- Hence we have to conserve them.
Sun:
- While the energy coming from sun in the form of sunlight is the pollution free and available in large amount which is free of cost also.
- The solar energy is the direct source of energy and also renewable.
- We can use solar energy in unlimited way which is available to us daily and it does not produces any pollution and no harms to the environment.
Alternative Answer –
Fossil fuels |
Sun energy |
Fossil fuels crates a polluted atmosphere in the environment. | Sun energy doesn’t create any kind of polluted atmosphere in the environment. |
These are the exhaustible sources of energy. | Energy from sun is the inexhaustible source of energy. |
It is a source of energy which is present in limited amount in earth. | It is a source of energy which is present in unlimited amount on the earth. |
It is a source of energy which is found deep in the earth. | It is a source of energy which comes from outside the earth. |
Fossil fuels can be obtained by giving the money. | It can be obtained by free of cost. |
5.) Compare and contrast bio mass and hydroelectricity as sources of energy.
Ans:
Biomass:
- The fuel sources like cow dung cakes, plant and animal products are said to be biomass. When these sources burns lot of smoke is produced with small heat.
- So some technologies are improved to get more heat energy. For this wood is burnt in limited supply of oxygen , water and volatile material present in it get removed remaining behind the charcoal.
- And these charcoal burns without flame, produces no smoke and which is having higher heat generation efficiency.
- Also, cow dung and various plant waste materials, residue after harvesting the crops, waste from green vegetables are decomposed in the absence of oxygen to produce bio gas.
- Bio gas is the most excellent fuel which contains 75% methane in it which burns without smoke and no residue will be left after its burning.
Hydroelectricity:
- To produce hydroelectricity, the high rise dams are build up on the rivers to stop the flow of water and to collect them in a large reservoirs.
- As the water level rises in dams the kinetic energy of flowing water is converted into potential energy. This water is provided to turbines through pipes from high level to the bottom of the dams. In this way hydroelectricity is generated which is pollution free but has certain problems also.
- Because dams can be constructed only in limited areas mostly in hilly terrains. While constructing dams large areas of agricultural land and human habitation get sacrificed. Also large ecosystem may get destroyed.
Alternative Answer –
Bio mass |
Hydro electricity |
1. Use of bio mass creates a polluted atmosphere in the environment. | Use of hydro electricity doesn’t create any polluted atmosphere in the environment. |
2. Bio mass can be obtained by free of cost. | If we construct a dam to get hydro electricity then it is an expensive project. |
3. It can be produced even in a small area of biogas plant. | To produce hydro electricity,we require large area of hydro power plant. |
4. It is a source of energy which is in the form of renewable. | It is a source of energy which is also in the form of renewable. |
5. It is a source of energy which can be obtained from dead plants. | It is a source of energy which is obtained from water. |
6.) What are the limitations of extracting energy from___
a) the wind?
b) the waves?
c) the tides?
Ans:
a) following are the limitations of extracting energy from the wind:
- Wind energy farms can be developed only in those areas where wind blows for a long time in a year. To rotate the turbine minimum 15km/h speed of wind is required.
- And for developing wind energy farms large area of land is required such as for 1MW generator, the land required may about 2 hectares.
- And also the initial establishment of wind farms takes high cost.
- The tower and blades requires high level of maintenance because they may get exposed to rain, sun, storm and cyclone also.
b) Following are the limitations of extracting energy from the waves:
- The wave energy is generated only where waves are very strong.
- And they are generated only by strong winds blowing across the sea.
c) Following are the limitations of extracting energy from the tides:
- The locations where dams are created for producing tidal energy can be limited.
Alternative Answer –
- To generate power from wind, first we need to find such a place where the wind speed should be 15 km/hr. There we can get wind power if we installe a windmill. Otherwise it is impossible to get energy from wind.
- We can get energy from waves only when there are strong waves in the ocean. It is impossible to get power from the waves if the wind does not cooperate to create strong waves in ocean.
- There is a need for dams to generate power from the tides, for which there is limited space to build dams properly. Also, since tidal variations are affected by the movement of the sun and moon, it is impossible to get energy from tides unless the tide is high.
7.) 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 are same?
Ans:
a)
Renewable sources of energy are those energy sources which are created again and again like biomass, sun, wind are the renewable energy sources.
And the energy sources which are not regenerated again are called as non renewable energy sources. The fossil fuels like coal and petroleum are the non renewable energy sources.
b)
- Exhaustible energy sources are those energy sources which may get destroyed after some time or may exhaust one day like coal and petroleum are the exhaustible energy sources.
- The energy sources which are not get exhausted after there use for many years like sun which is the most inexhaustible source of energy are the inexhaustible energy sources. And here the options a and b both are the same.
Alternative Answer –
- Some energy sources can be generated after we use them, we call such energy sources as renewable energy sources. Where as some sources of energy cannot be regenerated after we use them, such sources of energy are called non renewable sources of energy.
Examples for renewable energy sources: Sunlight, wave energy, water, biomass,etc.
Examples for non renewable energy sources: Petrol, Diesel, Gold, etc.
- As the years go by, some energy sources become depleted after we use, then such energy sources are called exhaustible energy sources. Whereas, No matter how many years pass, no matter how much you use some sources of energy, they never run out, then such energy sources we called inexhaustible energy sources.
Examples for exhaustible energy sources: Petrol, Diesel, Gold, etc.
Examples for inexhaustible energy sources : Sunlight, wave energy, water, biomass, etc.
Yes. Both options (a) and (b) are almost same.
8.) What are the qualities of ideal source of energy?
Ans: Following are the qualities of ideal source of energy:
- The ideal source of energy is that energy source which do large amount of work per unit volume or mass.
- That source must be easily accessible.
- That source must be easy to store and also to transport.
- And most importantly, that source must be economical.
Alternative Answer –
Qualities of an ideal source of energy.
- It shouldn’t create any polluted atmosphere in the environment.
- It should be available at low price.
- This should provide us with a large amount of energy.
- If we are to use this source of energy, it should be easy to use.
- This source of energy should be easily transportable.
9.) What are the advantages and disadvantages of using a solar cooker? Are there places where solar cookers would have limited utility?
Ans:
- Solar cooker uses solar energy for cooking food. And solar energy which is the renewable source of energy and cannot exhausted after its use.
- Therefore it is advantageous to use the solar cooker for food cooking.
- But, marinating and constructing solar cookers takes more cost.
- When there is no sunlight in rainy season we can’t use solar cookers.
- There are also some places where days are too short and cloudy sometimes throughout the year and there we can’t use the solar cooker due to the unavailable of solar energy.
Alternative Answer –
Advantages of solar cooker.
- It does not create any polluted atmosphere in the environment.
- A solar cooker is very easy to use.
- The solar energy used for this solar cooker is available freely.
Disadvantages of solar cooker.
- The food takes the longer time to cook in the solar cooker.
- Solar energy is not always available to a solar cookers.
- Not all types of food can be cook in it.
When the sunlight from the sun does not reach the Earth properly, and when there is no Sunlight during the night, during the rainy season and when the clouds are high in the sky, the sunlight does not reach the solar cooker. A solar cooker will not work in these above locations.
10.) What are the environmental consequences of the increasing demand for energy? What steps would you suggest to reduce energy consumption?
Ans:
- Due to the industrialisation and increase in population is responsible for the increasing demand of energy. Most of the usable energy sources are fossil fuels which are used in unlimited portion. Because of the burning of fossil fuels air pollution is creating which causes harm to environment also.
- And after some years these non renewable energy sources may exhaust. To keep energy sources for future generations we have to use renewable sources of energy such as solar energy, wind energy and so on.
- Which can be easily available and free of cost also. By using them we can also reduce the pollution and also energy consumption will be reduced.
Alternative Answer –
As the demand for energy in daily life is increasing, industrialization is increasing worldwide to meet that energy demand. In industry, when they burn different types of fossil fuel to meet the energy demand, carbon dioxide is produced by the combustion of these fossil fuels. Excess carbon dioxide production leads to global warming worldwide. To prevent all this, we should use energy only when it is absolutely necessary and if possible, use alternative fuels. And use as little energy as possible.