Bihar Board Class 10 Science Solutions Chapter 14 Sources of Energy

BSEB Bihar Board Class 10 Science Solutions Chapter 14 Sources of Energy Textbook Questions and Answers.

Bihar Board Class 10 Science Solutions Chapter 14 Sources of Energy

Bihar Board Class 10 Science Chapter 14 Sources of Energy InText Questions and Answers

In-text Questions (Page 243)

Question 1.
What is a good source of energy?
A good source of energy should have the following qualities:

  • does a large amount of work per unit mass.
  • cheap and easily available.
  • easy to store and transport.
  • safe to handle and use.
  • does not cause environmental pollution.

Question 2.
What is a good fuel
A good fuel should have the following qualities:

  • high calorific value (give more heat per unit mass).
  • bums without giving out any smoke or harmful gases.
  • proper ignition temperature.
  • cheap and easily available.
  • convenient to store.
  • bums smoothly.

Question 3.
If you could use any source of energy for heating your food, which one would you use and why?
I will use LPG (Liquefied Petroleum Gas) for heating my food; because it is easily available in my kitchen, gives no smoke on burning and takes less time to do the job.

In-text Questions (Page 248)

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

  • They are non-renewable.
  • They produce air pollutants on burning.

Question 2.
Why are we looking at alternate sources of energy?
Because of growing population, the energy demand is rising. Fossil fuels are going to be exhausted in the near future and burning them is causing pollution. Hence, we need to find an alternate source of energy which is renewable and environment friendly.

Question 3.
How has the traditional use of wind and water energy been modified for our convenience?
To use energy of flowing water, large dams are built to store huge amount of water at a height. The stored water is allowed to fall from a height which runs the turbine at the bottom of the dam to generate electricity. Similarly, the wind energy is used to generate electricity. For this purpose, the rotatory motion of windmill is used to turn the turbine of the electric generator.

In-text Questions (Page 253)

Question 1.
What kind of mirror; concave or convex or plain would be best suited for used in a solar cooker? Why?
A solar cooker uses heat of the sunlight to cook food. A concave mirror is used in order to reflect and focus sunlight at a particular area. The mirror focuses all the incident sunlight at a point. The temperature at the point increases, thereby cooking and heating the food placed in that particular area.

Question 2.
What are the limitations of the energy that can be obtained from the oceans?
Limitations of the energy obtained from the oceans are

  • There are very few locations where dams can be built to utilise tidal energy.
  • Cost of installation of power houses is extremely high and efficiency of plants is comparatively small.
  • Power plants built in oceans or at sea-shores will need high continuous maintenance as chances of corrosion are extremely high.

Question 3.
What is geothermal energy?
The energy which can be harnessed from the heat inside the earth is called geothermal energy.

Question 4.
What are the advantages of nuclear energy?
Advantages of nuclear energy:

  • A small amount of radioactive material can generate a huge amount of energy.
  • It does not produce air pollution.
  • A nuclear power plant is more efficient than other power plants.

In-text Questions (Page 253)

Question 1.
Can any source of energy be pollution free? Why or why not?
No sources of energy can be pollution free. This is because operation of a device like in a solar cell and some other sources of energy may be pollution free but their installation may cause pollution.

Question 2.
Hydrogen has been used as a rocket fuel. Would you consider it a cleaner fuel than CNG? Why or why not?
Hydrogen is a much cleaner energy source than CNG as it produces water vapour on burning. CNG (compressed natural gas) is derived from biomass and hence burning the CNG causes air pollution.

In-text Questions (Page 254)

Question 1.
Name two energy sources that you would consider to be renewable. Give reasons for your choices.
Biomass and solar energy because these sources can be easily replenished.

Question 2.
Give the names of two energy sources that you would consider to be exhaustible. Give reasons for your choices.
Coal and petroleum are two exhaustible sources of energy. These fuels were formed over millions of years ago and there are only limited reserves. If we continue to use them as at present rate, then these reserves will be exhausted very soon.

Bihar Board Class 10 Science Chapter 14 Sources of Energy Textbook Questions and Answers

Question 1.
A solar water heater cannot be used to get hot water on:
(а) sunny day
(b) a cloudy day
(c) hot day
(d) a windy day
(b) a cloudy day

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

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

  1. The reserves of fossil fuels are limited i.e., exhaustible.
  2. Burning of fossil fuels cause pollution.
  3. Fossil fuels can provide energy at any required time.

Solar energy:

  1. Solar energy is available in abundance i.e., inexhaustible.
  2. Solar energy is pollution free.
  3. Solar energy is available during daytime only and when there in no cloud.

Question 5.
Compare and contrast biomass and Hydroelectricity as direct sources of energy.

  1. The energy from biomass can be obtained by using a challah or a gobar gas plant.
  2. Biomass is pollution free when only biogas is used.


  1. Hydroelectricity requires construction of dam.
  2. Hydroelectricity is totally pollution free.

Question 6.
What are the limitations of extracting energy from: (a) the wind (b) waves (c) tides?
(a) Limitation of wind energy

  • Wind speed is not uniform always.
  • Big amount of investment is needed.
  • Need a large area for plant installation.

(b) Limitation of wave energy

  • Power output is variable in nature.
  • Wave energy generation is expensive.

(c) Limitation of tidal energy

  • Power output is variable.
  • Power generation is intermittent.

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?
Yes, options are same.
Renewable and inexhaustible sources of energy are similar to each other while non-renewable and exhaustible sources are similar.

Renewable sources of energy are those which are inexhaustible i.e., which can be replaced as we use them and can be used to produce energy again and again, Examples: (a) solar energy (b) wind energy

Non-renewable sources of energy are those which are exhaustible and cannot be replaced once they have been used.

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

  • Has high calorific value
  • Produces less smoke
  • Produces less residue after burning
  • Easy availability
  • Inexpensive
  • Easy to store and transport

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

  • Ecofriendly
  • Renewable
  • Used in rural areas
  • Retains all the nutrients in food due to slow cooking

Disadvantages of solar cooker:

  • Silicon cells are expensive.
  • Solar radiations are not uniform over the earth’s surface.
  • Cannot be used at night or on cloudy days.
  • Cannot be used to make chapattis for frying as these require a temperature of 140°C or more. (Maximum temperature of 100°C only can be achieved in a solar cooker)

Question 10.
What are the environmental consequences of the increasing demand for energy? What steps would you suggest to reduce energy consumption?
Environmental consequences:

  1. Air pollution is increasing due to burning of fossil fuels.
  2. Construction of dam destroys large ecosystem.

Steps to reduce energy consumption:

  1. Use energy efficient devices.
  2. Extract maximum possible energy from fossil fuels.

Bihar Board Class 10 Science Chapter 14 Sources of Energy Textbook Activities

Activity 14.3 (Textbook Page 244-245)

Discussion and conclusion:
The tennis balls acts like a turbine and starts rotating. It transfer its rotational energy to the dynamo, which converts it rotational energy to electricity. The electric current from the dynamo passes through the bulb and lights it up.

Activity 14.5 (Textbook Page 249)

Discussion and conclusion:
The conical flask which is painted black is hotter than the one painted white. Black colour absorbs more heat.