HBSE 10th Class Science Solutions Chapter 14 Sources of Energy

Haryana State Board HBSE 10th Class Science Solutions Chapter 14 Sources of Energy Textbook Exercise Questions and Answers.

Haryana Board 10th Class Science Solutions Chapter 14 Sources of Energy

HBSE 10th Class Science Sources of Energy Textbook Questions and Answers

Question 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
Answer:
(b) a cloudy day

HBSE 10th Class Science Solutions Chapter 14 Sources of Energy

Question 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
Answer:
(c) nuclear energy

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
Answer:
(c) nuclear energy

HBSE 10th Class Science Solutions Chapter 14 Sources of Energy

Question 4.
Compare and contrast fossil fuels and the Sun as direct sources of energy.
Answer:

Sun Fossil fuels
It is a renewable source of energy. It is a non-renewable source of energy.
It does not cause pollution. It causes a lot of pollution.
Solar energy is easily available at most of the places. Fossil fuels come at a high cost and that too they are not available at all places
It is initially expensive to harness solar energy. But, on a long run, it proves quite cost-effective. It is costlier to extract fossil fuels and even costlier to use on a daily basis.

Question 5.
Compare and contrast bio-mass and hydro electricity as sources of energy.
Answer:

Biomass Hydroelectricity
Using biomass as a fuel causes pollution. It does not cause pollution.
It is cheap and easily available on a daily basis. Its set-up cost is very high and it is not available everywhere.
Biomass energy can be harnessed with very basic knowledge and skills and labour without any government support. Highly skilled people, government support and time and labour are needed to develop a hydropower plant.

Question 6.
What are the limitations of extracting energy from:
(a) the wind? (b) waves? (c) tides?
(a) Limitations of wind energy:
Answer:
(a) Wind: Moving air is called wind.

(b) Wave energy:
The biggest limitation of this energy ¡s that it can be only obtained where waves are very strong.

(a) Tidal energy:

  • Tidal energy can be obtained only in coastal areas.
  • The electricity generated is in lesser quantity. So, its commercial use is not possible.

HBSE 10th Class Science Solutions Chapter 14 Sources of Energy

Question 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) the same?
Answer:
We can classify an energy resource as renewable or non-renewable on the basis of following difference.

Renewable/inexhaustible Non-renewable/Exhaustible
It the energy source is about to last almost perpetually, it can be classified as a renewable source. If the energy source is going to get exhausted in future, it is classified as non renewable.

The options given in (a) and (b) are same Le. renewable can be called inexhaustible and non renewable, exhaustible.

Question 8.
What are the qualities of an ideal source of energy?
Answer:
Qualities of an ideal source of energy:

  • The source of energy should be available In good quantity.
  • It should have good output i.e. it should be able to do a large amount of work per unit volume or mass.
  • It should be easily accessible.
  • It should be easy to store and transport.
  • It should be economical.

Question 9.
What are the advantages and disadvantages of using a solar cooker? Are there places where solar cookers would have limited utility?
Answer:
Advantages of solar cooker:

  • No fuel is required for combustion.
  • Maintenance is negligible.
  • It is pollution free.
  • The solar cooker conserves all the nutrients and vitamins and hence the natural taste of food is maintained.
  • No personal attention is needed while preparing food and so time is saved.

Disadvantages :

  • Food cannot be prepared on a cloudy as well as a rainy day.
  • Cooking in solar cooker consumes more time.

HBSE 10th Class Science Solutions Chapter 14 Sources of Energy

Question 10.
What are the environmental consequences of the Increasing demand for energy? What steps would you suggest to reduce energy consumption?
Answer:
Impact on environment due to Increasing demand of energy:

  • More the use of energy, more the pollution
  • Natural resources will deplete at a faster rate
  • Rise in global warming
  • Increase in acid rain which then damages crops, monuments, iron bridges and structures, etc.
  • Rise of sea-level

Steps to reduce energy consumption:

  • Use public transport as much as possible
  • Use bicycle or go walking to nearby places
  • Energy efficient lightening system, gadgets, buildings, etc. should be developed
  • Emphasis should be given on developing renewable energy sources

HBSE 10th Class Science Sources of Energy InText Activity Questions and Answers

Textbook Page no – 243

Question 1.
What is a good source of energy?
Answer:
Source of energy:

  • A source from which useful energy can be extracted either directly or indirectly by means of a conversion or transformation is known as the source of energy.
  • For example, sources of energy that provide us heat for cooking are LPG, kerosene, sunlight, etc.

Factors to consider while selecting an energy source:

  • The source of energy should be available in good quantity.
  • It should have good output i.e. it should be able to do a large amount of work per unit volume or mass.
  • It should be easily accessible.
  • It should be easy to store and transport.
  • It should be economical.

HBSE 10th Class Science Solutions Chapter 14 Sources of Energy

Question 2.
What is a good fuel?
Answer:
Characteristics of a good fuel:

  • The fuel should be cheap.
  • It should be easily available and in good quantity.
  • It should neither produce a lot of smoke nor leave a lot of residue.
  • It should have good thermal capacity.

Question 3.
If you could use any source of energy for heating your food, which one would you use and why?
Answer:
LPG and PNG are the best fuels when it comes to cooking.
Reason:

  • Both LPG and PNG are easily available and economical.
  • They have good calorific value.
  • They can be easily transported.
  • They do not cause pollution and also do not leave any residue after burning.
  •  In villages, gobar gas is considered as the best source of energy for cooking food. Gobar gas helps in getting rid of the waste generated, is a clean fuel and the residue works as an excellent manure.

Textbook Page no – 248

Question 1.
What are the disadvantages of fossil fuels?
Answer:
Disadvantages of fossil fuels:

  • Burning fossil fuels create smoke. This causes respiratory problems.
  • Fossil fuels such as coal and petroleum cause severe air pollution.
  • Acidic oxides of carbon, oxygen and sulphur are released on burning fossil fuels. These substances cause acid rain which affects our water and soil resources.
  • Release of carbon dioxide leads to the greenhouse effect which causes global warming.

Question 2.
Why are we looking at alternate sources of energy?
Answer:
1. Since several years the most convenient sources of energy for man are coal and petroleum. All these fuels are fossil fuels.
2. It takes millions of years for the formation of fossil fuels. But, man has almost emptied these fuels from the earth within few centuries.
3. Now, there is no possibility that man will be able to regenerate them. However, the demand is ever increasing due to rise in technology, population, inventions, etc. Hence, man is left with no option but to look for alternate sources of energy.

HBSE 10th Class Science Solutions Chapter 14 Sources of Energy

Question 3.
How has the traditional use of wind and water energy been modified for our convenience?
Answer:
1. Traditionally, wind and water energies were used to carry out basic tasks such as sailing boats, separating husk from wheat, drawing water from the earth using horses bullocks, watering farms using water wheels, etc.
2. In today’s time with advent of technology we use these sources of energy in several modern ways.
3. We have constructed dams to convert the energy of flowing water into electricity we have also set-up wind farms to produce electricity on large-scale commercial basis.

Textbook Page no – 253

Question 1.
What kind of mirror – concave, convex or plain – would be best suited for use in a solar cooker? Why?
Answer:
A plane mirror would be best suited in solar cooker. The reason for this is that plane mirror is a converging mirror. It reflects all the light falling on it and so more heat can be trapped in the cooker.

Question 2.
What are the limitations of the energy that can be obtained from the oceans?
Answer:
Energy from ocean is available in three forms. The limitations of each form are listed below.
(a) Tidal energy:

  • Tidal energy can be obtained only in coastal areas.
  • The electricity generated is in lesser quantity. So, its commercial use is not possible.

(b) Wave energy:

  • The biggest limitation of this energy ¡s that it can be only obtained where waves are very strong.

(c) Ocean thermal energy:

  • To obtain this energy it is necessary to have a temperature difference of 20° C or more between the surface water and water upto depth of 2 km. This increases the cost of production.

Question 3.
What is geothermal energy?
Answer:
Geothermal energy:
The deep interior region of the earth where magma is found is very hot. The energy utilized from this heat is called geothermal energy.

Question 4.
What are the advantages of nuclear energy?
Answer:
1. When the nucleus of a heavy atom (such as uranium, plutonium or thorium) is bombarded with low-energy neutrons, it gets split into lighter nuclei. This process is called nuclear fission.
2. During the splitting of nucleus, tremendous amount of energy is released. This energy is called nuclear energy.
3. The mass of the original nucleus which is bombarded is slightly more than the sum of the masses of individual nucleus formed.
4. The released energy can be used to produce steam and hence generate electricity.

Advantages:

  • The atomic fission of uranium produces 10 million times the energy produced by the combustion of an atom of carbon from coal.
  • The nuclear fuel can itself go on chain reaction and release energy at a controlled rate.

Textbook Page no – 253

Question 1.
Can any source of energy be pollution-free? Why or why not?
Answer:
1. Non-renewable sources cause a direct impact on environment that too at quite a fast pace.
2. In contrast to this we prefer alternative sources such as solar, CNG, hydro energy, etc and call them clean fuels.
3. Although these fuels are clean but in fact they are not fully clean. They are just cleaner than the renewable sources.
4. Generating solar power needs solar cells for which we extract silicon from earth. Similarly, we need materials like plastic, glass, etc. to make solar devices. Manufacturing or extracting these things causes damage to the environment.
5. Similarly, for constructing dams thousands of trees are cut and ecosystems are destroyed. Moreover, cement, iron and steel and several such materials are needed to build up hydropower plant. All these things cause environmental pollution or degradation.

HBSE 10th Class Science Solutions Chapter 14 Sources of Energy

Question 2.
Hydrogen has been used as a rocket fuel. Would you consider It a cleaner fuel than CNG? Why or why not?
Answer:
1. CNG releases carbon dioxide on burning but hydrogen does not. Moreover, hydrogen combusts completely. In these two aspects, hydrogen is a cleaner fuel than CNG.
2. On the flip side, we do not have proper technology to make hydrogen a domestic fuel like CNG. Hence, hydrogen cannot replace CNG in current scenario.

Textbook Page no – 254

Question 1.
Name two energy sources that you would consider to be renewable. Give reasons for your choices.
Answer:
(i) Energy obtained from biomass can be considered as a renewable source of energy because a lot of farm waste, plant waste and animal waste is produced continuously on a daily basis. All these wastes can be used to obtain biomass energy.

(ii) Energy derived from sun, flowing water, wind and ocean are also considered renewable because energy from these sources can be utilized as long as the solar system exists i.e. almost perpetual.

Question 2.
Give the names of two energy sources that you would consider to be exhaustible. Give reasons for your choices.
Answer:
1. Coal and petroleum are two energy resources that can be considered exhaustible.
2. These sources take millions of years for their formation and are likely to exhaust within next 200 years.

Activities

Activity 1.

Question 1.
List four forms of energy that you use from morning, when you wake up, till you reach the school.
Answer:
Although we see several forms of energies before we even reach our school, four of them are:
(i) Light energy (sunlight),
(ii) Heat energy (cooking),
(iii) Muscular energy (getting ready, bathing, etc.) and
(iv) Mechanical and electrical energy (Moving fan, mixer grinder, vehicle, etc.)

Question 2.
From where do we get these different forms of energy?
Answer:
Light energy from sun as well as electricity, heat energy from LPG/PNG, muscular energy from body, mechanical and electrical energy from various fossil fuels, etc.

Question 3.
Can we call these ‘sources’ of energy? Why or why not?
Answer:
Only fuel and sunlight can be called a source of energy. Rest all other are energies derived from some source.

HBSE 10th Class Science Solutions Chapter 14 Sources of Energy

Activity 2.

Question 1.
Consider the various options we have when we choose a fuel for cooking our food.
Answer:
We can either use heat energy of LPG/PNG to cook food or heat energy generated by electrical appliance such as induction.

Question 2.
What are the criteria you would consider when trying to categorize something as a good fuel?
Answer:
A good fuel should –

  • Have good calorific value
  • Be economical
  • Cause no or least pollution
  • Have easy accessibility and continuous supply
  • Be easy to handle and transport

Question 3.
Would your choice be different if you lived
(a) In a forest?
(b) In a remote mountain village or small island?
(C) In New Delhi?
(d) Five centuries ago?
Answer:
(a) In case of forests, our source of energy would be wood and leaves.
(b) In rural regions it would be cattle dung, wood from trees and twigs.
(c) Since New Delhi is a city, the source of fuel would be LPG or PNG.
(d) Before five centuries, the only fuel source known to man was wood.

Question 4.
How are the factors different in each case?
Answer:
Which fuel should be selected is dependent upon the availability of the fuel and its several characteristics such as calorific value, feasibility, etc.

Activity 3.

  • Take a table-tennis ball and make three slits into it.
  • Put semicircular HBSE 10th Class Science Solutions Chapter 14 Sources of Energy 1fins cut out of a metal sheet into these slits.
  • Pivot the tennis ball on an axle through its centre with a straight metal wire fixed to a rigid support. Ensure that the tennis ball rotates freely about the axle.
  • Now connect a cycle dynamo to this.
  • Connect a bulb in series.

Question 1.
Direct a Jet of water or steam produced in a pressure cooker at the fins as shown in the figure. What do you observe?
Answer:
Observation:
We can see that the bulb starts glowing. The bulb keeps on glowing as long as the source of fuel i.e. steam runs the turbine and dynamo.

Activity 4.

Question 1.
Find out from your grand-parents or other elders —
(a) How did they go to school?
(b) How did they get water for their daily needs when they were young?
(c) What means of entertainment did they use?
Answer:
(a) They used to walk, cycle or use bullock/horse cart for going to school.
(b) They used to draw water from the well, rivers and ponds.
(c) The means of entertainment they had were fairs, circus, stage drama, dance programmes, etc.

Question 2.
Compare the above answers with how you do these tasks now.
Answer:
(a) Today over and above bicycles, we also make use of fuel and even electric powered vehicles for going to school.
(b) We get water right in our bathrooms and kitchens through a property developed plumbing network.
(c) For entertainment we today have TV, mobile phones, theaters and malls, etc.

HBSE 10th Class Science Solutions Chapter 14 Sources of Energy

Question 3.
Is there a difference? If yes, ¡n which case more energy from external sources is consumed?
Answer:
Yes, there is a major difference. The energy consumed today is much higher than it was in the older times.

Activity 5.

  • Take two conical flasks and paint one white and the other black colour. Fill both with water.
  • Place the conical flask in direct sunlight for half an hour to one hour.

Question 1.
Touch the conical flasks. Which one is hotter? You should also measure the temperature of the water in the two conical flasks with a thermometer.
Answer:
The black flask is hotter than the white.

Question 2.
Can you think of ways In which this finding could be used In your daily life?
Answer:
From this activity we conclude that black ( and dark) coloured objects absorb more heat as compared to white or light colored objects. Because of these reasons we wear light coloured clothes in summer to reflect heat. Same principle is applied in the home interior. We use light colours on the walls so that more light is reflected and house looks spacious.

Activity 6.

Study the structure and working of a solar cooker and/or a solar water-heater, particularly with regard to how it is insulated and maximum heat absorption is ensured. Design and build a solar cooker or water-heater using low cost material available and check what temperatures are achieved in your system.

HBSE 10th Class Science Solutions Chapter 14 Sources of Energy 2

Construction :

  • The body of the solar. cooker is made up of wood, bad conductor material such as plastic or fibre.
  • The external surface of the solar cooker is coated with an insulated material to prevent loss of heat energy. The internal surface of the cooker and the containers used in it are of black colour to absorb maximum heat.
  • An adjustable plane mirror is fixed on the top of the box and it is adjusted in such a way that it can reflect maximum sunlight into the box. Moreover, the box is covered with another glass to retain the heat that goes into the container.
  • By exposing solar cooker under Sunlight for 2-3 hours continuously one can obtain a temperature of 100 °C to 140°  inside the cooker.

Uses:
Solar cookers are used to prepare food items such as rice, dal, pulses and vegetables.

HBSE 10th Class Science Solutions Chapter 14 Sources of Energy

Question 1.
Discuss what would be the advantages and limitations of using the solar cooker or water- heater.
Answer:
Advantages of solar cooker:

  • No fuel is required for combustion.
  • Maintenance is negligible.

It is pollution free.

  • The solar cooker conserves all the nutrients and vitamins and hence the natural taste of food is maintained.
  • No personal attention is needed while preparing food and so time is saved.

Disadvantages :

  • Food cannot be prepared on a cloudy as well as a rainy day.
  • Cooking in solar cooker consumes more time.

Activity 7.

Question 1.
Discuss in class the questions of what is the ultimate source of energy for bio-mass, wind and ocean thermal energy.
Answer:
Sun is the ultimate source of energy for biomass, wind and ocean thermal energy because –
(i) Plants i.e. the producers of ecosystem produce food through sunlight. Animals and humans get their food as fuel from plants and other animals.
(ii) Wind blows due to sun.
(iii) Ocean thermal energy can be harnessed because of temperature difference at the sea surface and deep water. The water on the surface is hot whereas deep water is quite cold.

Question 2.
Is geothermal energy and nuclear energy different in this respect? Why?
Answer:
1. Geothermal energy is developed due to presence and heat inside the earth. In this regard, geothermal energy is not directly dependent on solar energy.
2. Nuclear energy is also not dependent on sun because this energy is obtained due to nuclear reaction of radioactive substances.

HBSE 10th Class Science Solutions Chapter 14 Sources of Energy

Question 3.
Where would you place hydroelectricity and wave energy?
Answer:
Hydroelectricity and wave energy under renewable energy sources.

Activity 8 and 9.

Students should do these activities on their own.

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