This worksheet 12 contains questions based on Chapter 12 Sources and Energy with complete answers.
This
post explains the answers of questions given in the worksheet including
explanation, diagrams. These solutions will help you complete your assignments
and TMA also.
Sources and Energy
Worksheet 12 Solution
A
complete solution of Questions given in the worksheet 12 of Sources and Energy
of NIOS Class 10 Science.
Q1.
Energy is important in everyone’s life, whether you
notice it or not. Without sufficient energy people face difficulties doing
their day-to-day work. Observe your surroundings and list different sources of
energy, their importance and limitations.
Answer
Yes,
energy is very important for comfort, productivity and modern living. Almost
all human activities in daily life depend on one or another form of energy.
The amount of energy used by society indicates
the economic growth and development.
All
living beings also require energy for their physical activities and they get
from plants and plant need solar energy for photosynthesis to make food.
In the modern time, we are mostly dependent on
electricity which is used in each and every field of our daily life.
Without energy, we face difficulties in doing
a small work. Energy is required in every field; without energy all stops.
Different
Sources of Energy, Importance and Limitations
|
Sources
of energy |
Importance
|
Limitations |
|
Coal
|
Used
in producing electricity and running industries |
Non-renewable,
cause pollution and global warming |
|
Petroleum
|
As
fuel in vehicles, used in industries |
Limited
availability, cause pollution and increase greenhouse gases |
|
Natural
gas |
Used
in cooking, vehicles, cleaner than petroleum |
Non-renewable,
limited availability |
|
Solar
energy |
Used
in heating, cooking, generating electricity, renewable |
Installation
cost high, work only in sunlight |
|
Wind
energy |
Renewable,
can be converted into electricity |
Require
large space, works in windy areas |
|
Hydroelectrical
energy |
Renewable,
electricity is generated from running water in dams |
Dams
disturb biodiversity of the area |
|
Biomass
energy |
Wood,
cow dung, agricultural waste |
Produce
smoke and less energy is obtained |
|
Geothermal
energy/ocean energy |
Electricity
can be generated from earth’s heat and tides/waves |
Costly
technology, sites are limited |
Q2.
It can be observed easily that some of the energy
sources can be replenished in a short period of time while others take time and
even some can’t be replenished. Categorize and list sources of energy in
different categories on the basis of the statement.
Answer
Yes,
we can see different types of sources of energy, some are replenished in short
time but other cannot.
So, on the basis of this we can categorize energy source into two main types – (i) Renewable sources of energy (ii) Non-renewable sources of energy
(i) Renewable Source of Energy-
These sources of energy can be replenished
naturally in a short time and are inexhaustible.
Examples
a. Solar
energy – Energy from sun
b. Wind
energy – Energy from moving air
c. Hydroelectrical
energy- energy from running water
d. Biomass
energy – Energy from organic matter like wood, cow dung, agriculture waste
e. Geothermal
energy – Energy form heat inside the earth
f. Ocean
energy – Energy from waves, tides and ocean thermal energy
g. Hydrogen energy – Clean fuel obtained from water
(ii) Non – renewable Sources of Energy- These sources cannot be replenished and are exhaustible.
Example
a. Coal
b. Petroleum
c. Natural
gas
d. Nuclear
fuels like uranium and plutonium
Q3.
Explain source/sources of energy which leads to the
least environment pollution in the process of its harnessing and utilization.
Answer
We
classified the sources of energy into two categories – Renewable and
non-renewable. Renewable sources of energy cause the least environmental
pollution during their harnessing and utilization.
These
sources are clean, sustainable and do not harm environment during generating
energy.
Following
are the main sources of energy in this category
1. Solar energy – This type of energy is
obtained directly from the sun using
solar panels, solar cookers and solar heaters. They do not produce harmful
gases, smoke or noise so they are environment friendly.
2. Wind
energy – This energy is obtained by using windmill that
convert wind’s kinetic energy into electricity. This source of energy does not
cause air or water pollution so it is also environment friendly.
3. Hydroelectric
energy – This energy is generated from the running water in
dams using turbines. This source does not cause pollution so it is also
environment friendly.
4. Geothermal,
ocean and hydrogen energy- Energy is obtained from the heat
trapped in the earth, from waves/tides in the ocean. They produce negligible
pollution so they are also environment friendly.
Q4.
Ocean – A Big source of energy! Is this a
conventional or non-conventional source of energy? Write different ways of
harnessing energy from the ocean. Why is there a need to herness
non-conventional sources of energy?
Answer
Oceans
on the earth contains large amount of water. Energy obtained from the ocean is
called ocean energy which non-conventional and renewable.
Different
ways of harnessing energy from the ocean
Ocean
energy can be obtained in the following forms
1. Tidal energy – There are rise and fall of sea water levels due to gravitational pull of the moon and sun are called tides. Electricity is generated form tidal energy.
Tidal power plants are built in narrow inlets to trap water during high tides and release it during low tides to generate electricity.
2. Wave energy - Different types of waves
are continuously generated in the ocean every time. The back and forth or up
and down movement of waves is captured to harness the wave power by using a
turbine.
3. Ocean
Thermal energy – There is difference in temperature of
water on surface and deep in the ocean. This temperature difference is used to
run turbines and produces electricity.
Need to herness non-conventional sources of
energy
We
need to harness non-conventional sources of energy because of the following
factors:
1. Increasing
demand of energy
2. Limited
reserves of conventional sources like coal, petroleum and natural gas.
3. Conventional
sources cause pollution to environment.
4. Conventional
sources are non-renewable.
5. Non
– conventional sources are sustainable and renewable.
6. Non- conventional sources do not cause any
pollution.
Q5.
Observe your surroundings and you will find there
are source/sources of energy which causes environmental pollution. List them
and suggest steps to minimize environmental pollution caused by those
source/sources.
Answer
We
can see there are many energy sources that cause pollution and they are
conventional and non-renewable sources.
|
Sources
of energy |
Pollution
|
|
Coal
|
Produces
smoke, CO2, SO2 and ash and cause air pollution and
acid rain |
|
Petroleum
|
Burning
of petroleum release carbon mono oxide and unburnt hydrocarbons and cause air
pollution |
|
Natural
gas |
It
is cleaner than the above two but also release carbon dioxide in the air |
|
Wood
|
Release
smoke and cause air pollution and leading to respiratory problems |
|
Nuclear
fuels |
Cause
radioactive pollution |
Steps
to minimize environmental pollution caused by Conventional Sources
We
can minimize environmental pollution caused by conventional sources by
following steps:
1. By
promoting renewable energy
2. Turn
off lights and electrical appliances when not in use.
3. Use
CNG, LPG and biofuels
4. Grow
more trees to absorb carbon dioxide
5. Reduce,
reuse and recycle
Q6.
Sun is the ultimate sources of energy. Justify this
statement. How can solar energy be harnessed? Explain limitations in using
solar energy and suggest how these limitations may overcome.
Answer
Yes,
the sun is the ultimate source of energy and has been providing heat and light
for billions of years and will continue for billions of years.
The
sun is the source of all forms of energy available on the earth. Food energy
comes from solar energy through photosynthesis in plants.
The
energy in fossil fuels is stored solar energy in plants and animals that lived
millions of years ago.
Harnessing
of Solar Energy
Solar
energy can be harnessed in the following ways:
1. Solar cooker – This is a wooden box with
mirrors which concentrate and reflect sunlight for cooking food. This is a
simple and pollution free and economical way to use solar energy.
2. Solar
water heater – This device absorbs solar heat to warm water for domestic and
industrial use.
3. Solar
cell – These cells convert sunlight directly into electrical energy. These
cells are used in calculators, street lights. Solar cells are combined to form
solar panels.
4. Solar
power plants – these are large scale systems that use solar panels to generate
electricity.
Limitations
of Solar Energy
1. Solar energy is only available in day only.
2. The
installation of solar device or solar panels is high.
3. Maintenance
of devices is required time to time.
4. Requires
large area to set up solar plants.
Ways to overcome limitations of solar energy
1. Requires better storage systems
2. Improve
solar cell efficiency
3. Develop
hybrid systems combing solar with other renewable sources
Q7.
How will hydrogen as source of energy help in
reducing the emission of greenhouse gases and other pollutant? Also explain
challenges to use hydrogen as a source of energy.
Answer
Role
of Hydrogen in Reducing Greenhouse Gases and Pollution
Hydrogen
is a clean fuel and it can reduce greenhouse gases and other pollutants.
i).
By using hydrogen, we can reduce dependence on conventional sources like coal,
petrol and diesel which release large amount of CO2, SO2
and other pollutants.
ii).
When hydrogen burns, it produces only water vapour as a by-product which is not
harmful to the environment.
iii).
Engines powered by hydrogen is more efficient.
So,
hydrogen as energy source can prevent greenhouse gases and control global
warming.
Challenges
in using Hydrogen as a source of energy
There
are several challenges in using hydrogen.
1. Hydrogen
is not freely available and it has to be manufactured from water or
hydrocarbons and this process is also requiring a large amount of energy.
2. Hydrogen
is a light gas and requires high pressure and low temperature to store so it is
costly.
3. Transportation
of hydrogen is very costly.
Q8. “Law of Conversion of Energy” states that energy can
neither be created nor destroyed; it can only be transformed from one form of
energy to another. Observe your surroundings and give some examples of
transformation of energy taking place in our day-to-day life.
Answer
Law
of Conservation of Energy
The
law states that energy can neither be created nor destroyed, it can only be
transformed from one form to another, but the total energy of a system always
remains constant.
We
can see following energy transformation in day-to-day life
|
Situation/device |
Energy
transformation |
|
Electric bulb |
Electrical energy into light and
heat energy |
|
Electric fan |
Electrical energy into mechanical
energy |
|
Solar cooker |
Solar energy into heat |
|
Photosynthesis |
Solar energy into chemical energy |
|
Microphone and loudspeaker |
Sound into electrical and then
again into sound |
|
Battery in torch |
Chemical energy into electrical
and into light |
So,
these are some examples of energy transformation in our surroundings.
Q9.
Write an essay on Energy Crisis. Also suggest
measures to mitigate the problem of energy crisis in our country.
Answer
Energy
is the main key and driving force behind all human activities and economic development.
We need sufficient energy for our industries, transportation, communication,
agriculture and household activities.
But
due to increase in demand, we are facing shortage of energy sources, this is
called Energy Crisis.
Causes
of Energy Crisis
i).
Most of our energy needs are fulfilled by fossil fuels such as coal, petroleum
and natural gas. These sources are limited and non-renewable.
ii).
The increase in population and industrial activities raised the energy demand.
iii).
Due to poor energy management and careless use of electricity causes energy
loss.
iv).
There is unequal distribution of energy resources so it creates energy insecurity.
Reasons
behind Energy Crisis in India
India
has a large population and needs a large amount of energy to meet our daily
requirements for household, industries and transportation.
i).
Our over dependence on limited and exhaustible source of energy such as coal
and oil.
ii).
Increasing gap between demand and supply of the energy.
iii).
Increasing prices of the energy and fuel from other countries.
iv).
Hesitation in using alternative and renewable sources of energy like solar energy
v).
Overuse and misuse of available sources of energy
Measures
to Mitigate Energy Crisis
The
government as well as people should take collective steps to mitigate the
problem of energy crisis.
i).
One possible solution to India’s energy problems is Nuclear Power. These plants
must be set in the country to meet our energy demand.
ii).
The use of renewable sources of energy like solar power, wind power, hydroelectric
power, biogas should be promoted.
iii).
We should follow an ‘energy conservation approach’ in our daily life. We should
switch off lights and appliances when not in use.
iv).
We should research and develop modern technologies for renewable energy production
and storage.
v).
The government should promote biogas plants, solar cooker, and solar water heater
and should offer subsidies, incentives for renewable energy use.
Q10.
The key for resolving the country’s energy crisis
lays with the citizens. Among the things we can do is the conservation of our
non-renewable sources of energy. Write down the steps that you will take for
saving energy at home or workplace.
Answer
We
should take following steps to mitigate energy crisis:
i).
Energy saved is as good as energy generated, so, we should not Only use energy
but also save energy as much as we can. We should switch off the lights and
other electrical appliance when not in use.
ii).
Vessels should be covered when we cook food in them. If we soak pulses in water
for some time before cooking, it will save energy in cooking.
iii).
Use LED and CF in place of tube light or bulb because they are much energy efficient
and energy saver.
iv).
We should use public transport in place of using our own vehicle to save fuel.
v).
We should go to nearby place by a bicycle.
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