PSEB 10th Class Science Solutions Chapter 14 Sources of Energy

Punjab State Board PSEB 10th Class Science Book Solutions Chapter 14 Sources of Energy Textbook Exercise Questions and Answers.

PSEB Solutions for Class 10 Science Chapter 14 Sources of Energy

PSEB 10th Class Science Guide 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) cloudy day
(c) hot day
(d) windy day.
(b) cloudy day.

Question 2.
Which of the following is not an example of a bio-mass energy source?
(a) wood
(b) gobar gas
(c) atomic energy
(d) coal.
(c) atomic 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.
(c) nuclear energy.

Question 4.
Compare and contrast fossil fuels and the sun as sources of energy.

  • Both are natural sources of energy.
  • Both are widely used sources of energy.
  • No technology is required to get energy by any of these sources.


  • Sun’s energy can be used only during day time but fossil fuel can be used to get energy at any time during day or during night.
  • Solar energy is almost free whereas fossil energy costs much.
  • Infinite amount of solar energy is available almost free of cost whereas there is a limited reserve of fossil fuel.
  • Solar energy is a renewable source of energy whereas it takes millions of year to produce fossil fuel.
  • Solar energy is totally pollution free whereas fossil fuel causes a lot of pollution on burning.

Question 5.
Compare and contrast bio-mass and hydroeiectricity as a source of energy.

  • Both bio-mass and hvdro-electricity are natural sources of energy.
  • Working cost of both the sources of energy as low. However, initial installation cost of hydro-electricity sources is higher than bio-mass source.
  • Both are widely used sources of energy.
  • Hydroelectric plants can be erected only at specific points while biomass plant can be installed anywhere.
  • The energy produced by hydro-electric plant is much more than produced by biomass plant.


Biomass Hydroelectricity
1. Biomass is a renewable and conventional source of energy. 1. Hydroelectricity is also a renewable and conventional source of energy.
2. itse of biomass energy causes pollution of air. 2. Hydroelectricity does not cause any pollution of air.
3. Biomass possesses chemical energy. 3. Hydroelectricity possesses kinetic energy.
4. It does not cause ecological imbalance. 4. Construction of hydroelectric plant causes ecological imbalance.
5. It is economical source of energy. 5. It is relatively costly source of energy.

PSEB 10th Class Science Solutions Chapter 14 Sources of Energy

Question 6.
What are the limitations of extracting energy from :
(a) the wind
Limitations of Wind Energy.

  • It is not available at all times and at all places since it depends upon the availability of wind.
  • The minimum wind speed required to run windmills should be 15 km h_1.
  • The initial cost of construction of windmill farm is very high.

(b) waves
Limitations of wave energy.

  • The wave is not available at all times for generating electricity.
  • The power from wave energy is expensive because the plant required to be set up for trapping energy from waves is very costly.
  • The output power obtained from waves is not constant.

(c) tides
Limitations of tidal energy.

  • There are a few locations for constructing dams for harnessing tidal energy.
  • The power generation by harnessing tidal waves is very high because the cost of construction of dams for this purpose is very costly.

Question 7.
On what basis would you classify energy sources as :
(a) renewable and non-renewable.
(b) exhaustible and inexhaustible.
Are the options in (a) and (b) same?
(a) Renewable Sources of Energy. Those sources of energy which after depletion (used up) can be replenished (brought back to its original form) are called renewable sources of energy, e.g., water, wind, tides and ocean.
Those sources of energy which can not be replenished (regenerated) after when these are used up are called non-renewable sources of energy, e.g., fossil fuels, coal and petroleum.

(b) Exhaustible Sources of Energy. Those sources of energy which will get depleted some day are called exhaustible sources of energy. Exhaustible sources are non-renewable sources of energy.

Inexhaustible Sources of Energy. Those sources of energy which get replenished even after extraction of usable energy and are never depleted are called inexhaustible sources of energy. Inexhaustible sources of energy are renewable sources of energy.

Question 8.
What are characteristics of an ideal source of energy?
Characteristics of an ideal source of energy. An ideal source of energy should have the following qualities :

  • It should give adequate amount of energy at steady rate.
  • It should be safe and convenient to use.
  • It should do large amount of work per unit volume or mass.
  • It should be economical.
  • It should be easy to store and transport.

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

  • It saves fuel.
  • The nutrients of food do not get destroyed during cooking.
  • If does not produce pollution.
  • Its maintenance cost is low.
  • It is easy to handle and there is no danger of any mishap.

Disadvantages of using Solar Cooker

  • Solar energy is not available in ample amount and uniformly all the time and at all places. It cannot be used at night and on cloudy days.
  • Direction of reflector of solar cooker has to be changed continuously towards the direction of sun rays.
  • It can not be used for cooking chapatis or for frying purpose.
  • It takes more time to cook food.

Yes, there are places where solar cookers have limited utility. At poles solar cooker has limited utility because here sun remains absent for six months. In hilly areas also the sun has limited utility because the sun shines for limited time and where inclined sun rays reach, the use of solar cooker becomes difficult.

Question 10.
What are environmental consequences of the increasing demand for energy? What steps would you suggest to reduce energy consumption?
The demand of energy is increasing day by day. Exploiting any source of energy may disturb the environment in one way or the other. For example, getting energy from fossil fuel may cause air pollution and getting energy by nuclear fission may create problem of disposal of nuclear waste.

Steps for reducing energy consumption should be such that we get maximum energy from least fuel.
For this :

  • Under the given situation the best possible technology should be utilised. For example, smokeless chullahs should be preferred to traditional chullahs.
  • Energy should he extracted by most economic method under the given situation. Whereas energy extraction by solar cell may be useless in big towns due to cost factor, it may be indispensable for artificial satellites.
  • Energy saved is energy produced. Therefore, wastage of energy should be strictly avoided.
  • Sources of energy should be such that it causes least damage to environment.

Science Guide for Class 10 PSEB Sources of Energy InText Questions and Answers

Question 1.
What is a good source of energy?
Write characteristics of an ideal source of energy.
Characteristics of a good source of energy are :

  • It should be sustainable and renewable source of energy.
  • It should provide great amount of energy per unit mass or volume.
  • It should be easily accessible and provide energy for a longer period of time.
  • It should not cause pollution.
  • It should be economic to use.
  • It should be safe for the surrounding individuals.

Question 2.
What is a good fuel?
What are the characteristics of an Ideal fuel?
Give three characterisitcs of a good fuel.
Give the properties of an ideal fuel.
Characteristics of a Good Fuel. A good fuel is that which :

  • Has high calorific value when burnt it should produce large amount of heat per unit mass.
  • Should produce less smoke or preferably no smoke and should not leave any residue (ash).
  • Should be economical (low cost).
  • Should produce no pollution.
  • Should have steady rate of combustion.
  • Should be easy to store and produce no hazard to transport and easy to handle.

Question 3.
If you could use any source of energy for heating your food, which one would you use and why?
For heating my food I would use fuel which fulfills the most of the characteristics of a good fuel such as

  • high calorific value
  • pollution free
  • easily available
  • cheap.

For this I would use L.P.G. if living in a city and wood/gobar gas if living in a remote village.

Question 4.
What are the disadvantages of fossil fuels?
Disadvantages of fossil fuels (Non-renewable fuels) :

  • Burning of fossil fuels such like petrol, diesel, coal, natural gas etc. causes air pollution.
  • Burning of fossil fuels produces carbon dioxide (CO2), a green house gas which causes global warming.
  • On burning fossil fuels, oxides of carbon, nitrogen and sulphur are released. This leads to acid rain which affects our soil and water resources.
  • There are limited resources of fossil fuels since these were formed over millions of years and their continuous use would exhaust them and make them unavailable after some time.

Question 5.
Why are we looking at alternative sources of energy?
With the development of technology and swelled up population, the demand for energy has increased manifold which cannot be met with traditional non-renewable sources. We are, therefore, looking for alternative sources of energy because :

  • Fossil fuels like coal and petroleum which are traditional sources of energy are non-renewable and are not going to last long.
  • The traditional sources of energy are costly and cause pollution whereas alternative sources of energy like solar energy, wind energy and water energy do not cause pollution and are almost free of cost except for their installation cost.

Question 6.
How has the traditional use of wind and water energy been modified for our convenience?
Traditional use of wind energy was made to lift water from the well and run grinding machine to grind grams. The traditional use of wind energy has now been modified to generate electicity where turbines are made to rotate by the use of wind energy.

Likewise, the traditional use of water energy has been modified to generate electricity in hydropower plants. Water is collected in dams. It is then made to fall on turbines where potential energy of collected water is transformed into kinetic energy of running water which is made use of in running turbines and thus converting into electricity.

Question 7.
What kind of mirror-concave, convex or plane would be best suited for use in a solar cooker? Why?
A concave mirror is the best for use in solar cooker for it focuses sun rays from large areas to a specific point. These concentrated heat rays produce large amount of heat at that point.

Question 8.
What are the limitations of the energy that can be obtained from the oceans?
The energy obtained from oceans can be of the following kinds :
1. Tidal Energy. Due to attraction of the moon, there are high and low tides in the sea. Tidal energy is harnessed by constructing dam across a narrow opening in the sea and a turbine fixed at this opening converts tidal energy of waves into electricity.

The limitation of this kind of energy is there are only a few such locations available where dams can be constructed for production of energy. Therefore, this kind of energy will not be enough for commercial use.

2. Ocean Thermal Energy (O.T.E.) Due to sunlight, water at the surface of the ocean gets heated up while water in the deeper regions is relatively cold. This difference in temperature is exploited to get electric energy which is called ocean thermal energy. But the limitation of conversion efficiency is very low. These plants for generating electricity is that these plants work only when the temperature difference of water at the surface and at the depth upto 2 km is 20° C or more. Secondly, its operational cost is high and the efficiency is very low.

PSEB 10th Class Science Solutions Chapter 14 Sources of Energy

Question 9.
What is Geothermal energy?
Geothermal energy. Due to changes taking place within earth, molten rocks formed in the deeper hot regions of earth are pushed upward in the regions called ‘hot spots’. Steam is generated when underground water comes in contact with hot spots. The energy which is directly obtained from the heat inside the earth is called geothermal energy. Steam trapped in is passed through a pipe to the turbine can generate electricity.

Question 10.
What are the advantages of nuclear energy?
Advantages of Nuclear Energy.

  • A smaller space is required to get nuclear energy.
  • Nuclear energy is a non-conventional source of energy and produces large quantity of usable form of energy.
  • It costs less.
  • It is almost pollution free energy.

Question 11.
Can any source of energy be pollution free? Why or why not?
Name two energy sources that you consider pollution free. Give reasons.
No source of energy can be perfectly pollution free e.g., bio-mass energy, hydro energy, wind energy, geothermal energy, solar energy is almost pollution free but the process involved in making these plants might have damaged the environment in some way.

Question 12.
Hydrogen has been used as a rocket fuel. Would you consider it a cleaner fuel than C.N.G.? Why or why not?
Hydrogen is a cleaner fuel than C.N.G. because the burning of hydrogen produes water which does not pollute the atmosphere. On the other hand, C.N.G. when burnt produces carbon dioxide and water. This carbon dioxide does produce greenhouse effect which ultimately leads to heating of environment. Hence, hydrogen is positively a cleaner fuel than C.N.G.

Question 13.
Name two energy sources that you would consider to be renewable. Give reasons for your choice.
Two renewable sources of energy are :
1. Hydro energy. It is the energy generated by using kinetic energy of running water to run dynamo. Hydro power is the main source of electricity now a days. Down from high altitude is utilized to trap energy for generating electricity and the unused water utlimately goes to oceans.

Due to cyclic process (water → water vapour → clouds → rain→snow→running water at dams) again we get water. Water stored in reservoirs at dams is used for generating electricity. So hydro energy is a renewable source of energy.

2. Wind Energy: Wind energy is the kinetic energy due to motion of large mass of air. Wind energy can be used to sail boats, run windmills to produce electric power. Sun rays near the equator are stronger than in the polar region. As a result, air in the equitorial region becomes hot and rises up while cooler air in the polar region moves towards the equator. This causes the flow of air (wind). This process goes on in nature due to temperature differences, so wind energy is a renewable form of energy.

Question 14.
Give the names of two energy sources that you would consider to be exhaustible. Give reasons for your choice.
Coal and petroleum are two energy sources which are exhaustible. It takes millions of years for the formation of petrol and coal inside the earth. Its reserves are limited. Coal if used at the present rate will not last beyond two hundred years whereas petroleum products which are being used extensively are expected not to last more than 50 years. Therefore, these energy sources are exhaustible in nature.

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