ENERGY: Energy is defined as the ability or capacity to do

work.

Fuel: The substance that reacts chemically with another

substance to produce heat is called fuel.
For e. g coal, petroleum, solar, biomass, etc.

Classification of energy source:

I. On the basis of form of used, source of energy are classified in
two ways:
a) Primary source of energy: Those source of energy which
can be used in the same form in which they occur in
nature are called primary sources .e.g. wood, coal, natural
gas, dung, solar energy etc
b) Secondary source of energy: Those sources of energy
which are derived from primary source are called
secondary source. For e.g. coal gas, biogas, kerosene,
petrol diesel, charcoal etc.

ii. On the basis of replacing period, energy source are classified

into two types:
a) Non-renewable energy sources: The source of energy which
takes millions of years to build up and once exhausted are not
easily available again are called non-renewable source of
energy.
E.g. coal, natural gas, petroleum, nuclear energy etc.

~1~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 1
 b) Renewable source of energy : The source of energy which
can be re-produce in short time and can be used continuously
for a long time are called renewable source of energy. for
e.g. wood , hydropower, geothermal power, solar energy, wind
energy ,tidal energy etc. they are inexhaustible in nature

Q) Difference between
Non renewable resource of Renewable resource of energy
energy
1) They are exhaustible 1) They are inexhaustible
2) They are mostly 2) They are non-polluting to
polluting to nature nature
3) They take long time to 3) They can be generated in
reproduce short period of time
e.g., coal, petroleum e.g. biomass,
,natural gas hydroelectricity solar energy

Some examples of renewable source of energy:

A) Hydropower / hydro energy:
The power obtained from water is called hydropower. If the
hydro energy is used to generate electric current then it is
called hydroelectricity. In hydropower, K.E of fast running
water is converted into electrical energy. Water is collected
by constructing a high dam for electrical energy. Such
~2~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 2
 collected Water has enough P.E when it flows from the great
height then PE is converted in to K.E. This moving water is
allowed to fall on blades of water turbine. The K.E of flowing
water rotates the turbine rapidly, which rotates the armature
of the generator producing electricity. The largest source of
renewable energy in world is hydroelectricity. It has been
estimated that total hydropower capacity of Nepal is about
83000MW. But at present day 1800MW of Electricity is being
produced through different hydropower project.
Advantages of hydroelectricity / Hydropower:-
➢ It doesn’t pollute environment.
➢ It is renewable source of energy.
➢ It has multipurpose use.
➢ Although initial construction cost is expensive, it seems to
be cheap in long run.
Disadvantages of Hydroelectricity:-
➢ The large number families of human are affected.
➢ The fertility of downstream area of dam is reduced
➢ The life of aquatic animals in the downstream of dam is
greatly affected.
Application of hydroelectricity:-
• It is used in transportation.
• It is used in industries to operate various machines
• It is used in irrigation for agriculture

~3~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 3
 • It can be used for various household purposes such as
cooking ,heating , washing ,cooling etc
B)Tidal energy:
The energy developed by tides is tidal energy. The tidal wave in
the ocean builds up and down twice a day. The rise of ocean
level due to the attraction of the moon is called high tide
whereas the fallen of ocean level is called low tide. The water
raised during the high tide is trapped in dams and this water
allowed to fall down slowly on blades of water turbines. The
rotating turbine drives generator, which ultimately produce
electricity.
Use of tidal energy:-To produce electricity
Advantages of tidal energy: It is available free of cost & is
pollution-less.
Limitation of tidal energy:-electricity cannot be generated in
large scale.
C) Wind energy: -
Wind energy is the KE associated with large mass of air by
virtue of its motions. Wind energy is the largest & the most
available form of renewable energy today. The K.E of moving
air has been traditionally used to pump water & to run flour
mills & to generate electricity from wind energy.
Use:- It is used to generate electricity and to move sail boats
Advantages:- It is free of cost and doesn’t cause any
environmental pollution

~4~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 4
 D) Geo-thermal energy: -
The energy present as heat (thermal) on earth Crust is called
geothermal energy .The core of the earth is extremely hot.
When water is sent in the core of the earth, it is readily
vaporized. The Water Vapor is used to run steam engines for
generating electricity. Thus the energy which is obtained
from the core of the earth is called geothermal energy.
Use: Direct use of it is for heating building, growing crops,
drying fruits & vegetables.
It is used to control building temperature above ground &
for generating electricity.
Advantage of geothermal energy: It doesn’t cause any
environment pollution.

E) Bio-mass energy:-
The material of the plant and animal origin is called biomass.
eg. Dry wood, dry weeds, agriculture waste, animal dung etc.
are Biomass.
The energy obtained by the burning of biomass is called
biomass energy. It is renewable source of energy.
a) Bio gas: CH4, H2, CO2 and H2S gases produced on
degradation of biomass by the anaerobic bacteria, called
biogas. It is also called GOBAR GAS. BIOGAS is a mixture
contains in 55%-65% methane, 30%-40% carbon dioxide with
~5~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 5
 a small amount of other gases and water vapor. It can be
produced by decomposition of animal wastes like cattle
dung, crop residue, human excreta and feces matter and
waste from sugarcane.
b) Biogas plant: The physical installation to produce biogas
from biomass is called biogas plant.
➢ Use of biomass fuel
➢ The biomass fuel can be used in cooking and heating in
houses
➢ The biogas is used for lighting
➢ The biogas is used to run engines such as water pump
Advantages of using biomass fuel ( biogas):-
➢ The biogas is cheaper than any other fuel because the raw
materials needed for production of biogas are not costly and
are locally available.
➢ It has large caloric value and is clean fuel and doesn’t
produce harmful gases thus it doesn’t cause air pollution.
➢ After the decomposition of biomass then residue left is
good manure.
➢ Its use controls the consumption of nonrenewable source
of energy.
F) Solar energy:-
The energy emitted by the sun is termed as solar energy. Solar
energy is directly used to produce heat and also used to

~6~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 6
produce electricity. The device which converts solar energy
into other form of energy is called solar devices.
eg. Solar cooker, solar heater, solar cells, solar power plants
etc
Advantages: It is pollution free and an inexhaustible source of
energy.
Disadvantages:
➢ Solar energy is not available in sufficient amount at all the
time.
➢ Its storage is problematic.
Application of solar energy
➢ It provides light energy
➢ It provides warmth on the earth surface.
➢ It regulates the flow of wind and water cycles on the
earth.
➢ It helps the plants to grow which in turn provides food to
us
Solar constant:
The solar energy falling per second per unit area of the earth
from the sun is called solar constant & its value is 1350Wm-2.
The amount of solar energy that arrives at the earth's surface
is constant. It depends on geographical location, time of day,
time of year & weather conditions.

~7~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 7
Some examples of non-renewable sources of energy:
A) Fossil Fuel:
The remains of plants and animals burred under the earth
millions of years ago; such preserved dead bodies are called
fossils. These fossils are excellent fuels called fossil fuel. Coal
and minerals oil are fossil fuels as they are formed from the
dead bodies of plants and animals. .
a).Coals:
Coal is a black rock like materials which is a complete mixture
of compound of carbon, hydrogen and oxygen. Coal is known
as fossil fuel as it is obtained from the organic matter buried
under the earth. It is a non-renewable source of energy. It is
the main source of various industries like iron and steel,
cement, brick etc. It is possible to make liquid fuel such as
diesel & jet fuel from coal. In the United States, 49% of
electricity generation comes from burning coal.

Carbonization: The formation of coal from organic matter

under high temperature and pressure is called carbonization.

Type of coal: Lignite (low quality coal), Sub-bituminous,

Bituminous (soft coal) & Anthracite (Hard coal i.e. high quality
coal)
Uses of coal
➢ It is used as a fuel in stream engine, cooking, thermal
power station and industries.

~8~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 8
 ➢ It can be converted into other sources of energy as coal
gas , oil and electricity
➢ It is essential for the manufacture of drugs, dyes,
fertilizers, plastic, synthetic fiber etc.
b). Petroleum (mineral oil or crude oil) : (petro=rock &
oleum=oil)
Mineral is a dark colored viscous liquid and is complex mixture
of compounds containing mainly carbon and hydrogen.
Petrol, diesel, kerosene, paraffin etc are petroleum.
Crude Oil: Minerals oil extracted from well is crude oil that
contains 90%-95% hydrocarbon.
Uses of petroleum:
Minerals oil or petroleum is used in transportation.
i. It is used in heating purposes, lighting purposes etc
ii. It is used in generating electricity.
iii. It is used to power various heavy and light machines in
industry.
c).Charcoal:
It is a blackish residue consisting of impure carbon obtained by
removing water & other volatile constituents from animals &
vegetation substances. It is usually produced by slow
Pyrolysis(transformation or shift), the heating of wood, sugar,
bone, char or other substances in the absence of oxygen

~9~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 9
Use:
➢ It is used as cooking fuel, automotive fuel, and purification
& filtration process.
➢ It is used in art for drawing & making rough sketch in
painting.
➢ It is also used in smoking of the Hookah

d). Natural gas:

The gaseous mixture of lower hydrocarbons which occurs deep
inside the earth either alone or covering the crude oil in an
oilfield is called natural gas. It mainly consists of Methane. it is
an important feedstock for fertilizers & a potent greenhouse
gas.
Use: It is used for power generation, Domestic purpose,
Transportation fuel, fertilizer purpose, to produce Hydrogen,
glass, plastics, paints & other products.

Q. How is enormous energy produced from the Sun?

Nuclear fusion is the source of solar energy. The sun is rich in
hydrogen gas. At very high temperature of the sun, hydrogen
atom splits up into protons and electrons. Although, there is
repulsion between protons, very high pressure of the sun binds
two protons (1H1) to form a deuteron (1H2) and a positron (1e0).
A proton (1H1) and a deuteron or deuterium (1H2) combines to
form the light isotopes of helium (2He3). Them the two nuclei of
light helium (2He3) combine to form ordinary Helium nucleus
(2He4) with some hydrogen nuclei. In each step of nuclear fusion
a vast (huge) amount of energy is released.

~ 10 ~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 10
 1 + 1H1 2
+ 21eO + Q (energy)]*2
1H 1H
2 1 3
1H + 1H 2He + Q (energy)]*2
3 3 4 1 1
2He + 2He 2He + 1H + 1H + Q (energy)

In short 21H1 + 21H1 2He

4 + 21eO + Q (energy)

Condition required to nuclear fusion in the sun

a) There is an abundance of hydrogen gas in the sun to
participate in nuclear fusion.
b) Extremely high temperature of sum (108) causes hydrogen
atoms to split their nuclei.
c) Extremely high pressure of the sun causes the similar charged
nuclei to fuse together.

Evidence of nuclear fusion in the sun

➢ The sun has huge amount of hydrogen which participates in
the nuclear fusion.
➢ There is presence of abundance of helium gas on the sun,
which is the product of nuclear fusion
➢ There is high pressure of the sun to unite the similar charge
hydrogen nuclei.
➢ The presence of helium in the sun which is the product of
nuclear fusion.

NUCLEAR ENERG (NUCLEAR FUEL):

The energy released by splitting (fission) or combining (fusion)
of the nuclei of an atom is called nuclear energy. The must use
of nuclear energy is to generate electricity.

~ 11 ~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 11
PRINCIPLE OF GENERATION OF ELECTRIC ENERGY FROM
NUCLEAR ENERGY:
The heat produced in a controlled nuclear fission is used for
producing steam. The steam so produced runs the turbine. The
rotator motion of the turbine rotates the alternator of the
generator & electricity is produced. Thus, in a nuclear power
plant, the energy transforms in the following sequence:
Nuclear energy of Uranium-235 nucleus → Heat energy of
steam →Kinetic energy of turbine→ Kinetic energy of
Alternator →Electrical energy.

Advantage of Nuclear Energy:

➢ It is used to generate electricity
➢ 1 gram of Uranium produce large amount of energy
➢ It does not pollute the environment.
Disadvantage of nuclear energy:
➢ Nuclear explosion produce radiation, which harms the
cells of the human body.
➢ Nuclear reactors have also waste disposal problems.
➢ Nuclear reactors only last for about forty to fifty years.

Advantage of fossil fuel

➢ It is relatively cheaper than other fuels.
➢ It can be transported easily
➢ It has high caloric value than other
Disadvantage of Fossil fuel
➢ It creates Environmental pollution & Responsible for
Global warming.

~ 12 ~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 12
 ➢ It directly as well as indirectly affects Human Health
➢ SO2 is one pollutant which is released when fossil fuel
are burnt & is main cause of Acid rain
Energy crisis:
The future scarcity of energy source on the earth due to over
population, urbanization and industrialization is called energy
crisis.
Factors responsible for energy crisis:
➢ Use of non-renewable resource of energy.
➢ Growing population which requires more energy
consumption
➢ Rapid industrialization
➢ Advance style of life increases consumption of energy

Energy conservation /Energy saving

➢ By controlling the population growth
➢ By using solar device and nuclear energy
➢ By developing and use of alternative source of energy
➢ In context of Nepal, Energy conservation can be done as
a) By using more Bio-fuel, solar energy, wind and wave
energy.
b) By controlling over population
c) By using and producing more hydroelectricity

ALTERNATIVES SOURCE OF ENERGY:

Energy sources which can be used to preserve the non-
renewable source of energy for the future are called

~ 13 ~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 13
Alternative source of energy. It is used to save from energy
crisis.
e.g. Bio-fuel energy, Wind energy, Geothermal energy, Tidal
energy ,Nuclear energy etc
SOLAR DEVICES:
The devices which convert solar energy into heat energy &
electrical energy are called Solar Devices & corresponding
devices are called Solar heating device & Photovoltaic cell.
The solar heating devices convert solar energy to Thermal or
Heat energy & used to
a) Heat water- for use in home, building or swimming pools
b) Heat space -inside greenhouse, homes or other building
c) solar space heating systems can be classified as passive or
active
Passive solar heating does not include any kinds of
mechanical heating device whereas active solar heating
system needs use of electrical or mechanical equipments
such as pumps, fans etc

Solar or Photovoltaic cells:

A device that converts sunlight directly into electric current is
called solar or photovoltaic cell. It is based on the Photoelectric
effect. It is made from semiconducting P-% N- type Silicon. The
first solar cell was constructed by Charles Frits.
Currently the best designed cells can generate a 40 Wm-2 in
bright sunlight, with maximum transfer efficiency of 24%. The
world most powerful Solar cell power plant is the 20 Megawatt
in Spain.
~ 14 ~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 14
GREENHOUSE EFFECT:
[WHAT IS GREENHOUSE EFFECT? DISCUSS ITS EFFECT,
SOURCES & CONTROLLING MEASURES]
The atmosphere of the earth acts as a blanket & the solar
radiation is trapped so that the temperature of the earth
increases. This is called greenhouse effect. A greenhouse is a
house whose walls are made up of green glass which traps the
radiation inside it.

Sources of greenhouse gases

➢ Methane gas (CH4) comes from domestic waste & dung
➢ Nitrous Oxide (NO2) from soil
➢ CFC gas comes from burning of foam products , use of
refrigerator ,air conditioners etc
➢ CO2 & CO comes from burning fossil fuels, gases ,
automobiles , thermal plants ,industrial activities
➢ Deforestation & reduction of ground cover

Effect of greenhouse effect:

➢ Ozone layer depletion
➢ Global warming
➢ Sea level rise
➢ Strong storms & extreme events
➢ Smog & ozone pollution
➢ Changes to plant growth & nutrition levels
➢ Increased melting of snow & ice

~ 15 ~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 15
 Ways to control greenhouse effect:
➢ by increasing forestation
➢ by reducing use of fossil fuels
➢ by banning deforestation & use of CFC's
➢ by using biogas for domestic purpose
➢ by reducing use of heat & air conditioning
➢ Drive less & drive smart
➢ encourage others to conserve
➢ by using alternative source of energy
➢ by energy-efficient products

ACID RAIN:
The rain that contains harmful chemicals like Carbonic acid,
Sulphuric acid, nitric acid etc that damages trees, crops,
building is called Acid Rain. The harmful gases like carbon
dioxide, sulphur dioxide, nitric oxide coming from industries &
other sources mix with water during the rain then the rainfall
form in the acid which is called Acid Rain.
An example of reaction producing acid rain is given below:
2SO2 + O2 → 2SO3
2SO3 + H2O → H2SO4 ( Sulphuric acid)
For HNO3
NO + O3 → NO2+O2
2NO2 +O →N2O5
N2O5 + H2O → HNO3 (nitric acid)

~ 16 ~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 16
EFFECT OF ACID RAIN:
➢ It increases the soil acidity & reduces the crop yield.
➢ It increases acidity of water in the pool, rivers, lakes seas
etc & likes aquatic animals.
➢ Acidic water may cause respiratory & skin diseases
➢ It helps to spread bacterial disease
➢ It corrodes building, bridge, monuments etc.

OZONE LAYER DEPLETION (EFFECT OF CFC's ON OZONE

LAYER):
Ozone is a pale blue gas which is made up of three oxygen
atoms & its molecular formula is O3. It is found in the
Stratosphere. The gas layer formed by ozone in the
Stratosphere is called the Ozone layer.
When the gases like CFC’s, CO, Oxides of Nitrogen (NO,NO2,
N2O), Methyl bromide(CH3Br), Chloroform(CHCl3) etc reach in
the stratosphere of earth atmosphere , they decomposed by
UV radiation & form Chlorine. This chlorine helps to
decompose Ozone & hence amount of ozone is drastically
reduced there. This is called Ozone layer Depletion.
𝑈𝑉 𝑟𝑎𝑑𝑖𝑎𝑡𝑖𝑜𝑛
CFC's → CFCl2 + Cl(nascent chlorine)
The chlorine then directly attacks the Ozone as:
Cl + O3 →C + O + O2
2ClO → 2Cl + O2
The chlorine thus formed again attacks another O3. The
process goes on a cyclic manner & it is estimated that CFC's
molecule can destroy 10,000 molecules of O3.

~ 17 ~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 17
Similarly, when the oxide of nitrogen reaches the stratosphere,
they react with O3 forming O2 according to following reaction:
NO + O3 → NO2 + O2
2NO2 + O3 → N2O3 + 2O2
In this way, the layer of Ozone in the atmosphere is depleted
due to the action of CFC's products & the oxides of nitrogen.

EFFECT OF OZONE LAYER DEPLETION:

The Ozone layer in the Stratosphere absorbs various harmful
Ultraviolet (UV) radiations coming from the Sun & outer
Surface, & saves lives on the Earth from their adverse effect.
The major destructive effects are as follows:
➢ Increase in temperature & effect on human health
➢ Over exposure of UV radiation can cause skin burning
(skin, lungs, breast cancer, blindness)
➢ The depletion of Ozone layer cause eye cancer in castles
➢ The depletion of ozone layer may leads to loss of various
plants form terrestrial & aquatic habitats.
➢ It may brings change in climate & cause green house effect
➢ It reduces crops productivity & damage the ecosystem.
Protection of Ozone layer:
➢ By banning the production & use of CFC's
➢ By avoiding the release of oxides of Nitrogen
➢ By bringing awareness of ozone depletion in people
➢ By finding the alternatives for CFC's products

~ 18 ~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 18
IMPORTANCE OF OZONE LAYER:
Ozone layer checks most of the UV radiation coming from the
sun. As a result, the harmful radiation cannot reach the earth's
surface. Ozone layer helps to preserve the aquatic &terrestrial
ecosystem on the earth. Thus, organisms survive from its bad
effect.

GLOBAL WARMING:
The increase of average temperature of the world is termed as
global warming. The earth's average temperature rises about
0.6°Celsius (1.1°F) in the 20th century.

CAUSES OF GLOBAL WARMING:

➢ Greenhouse gases: Greenhouse gases like CFC's , CH4, CO,
CO2, SO2 etc are those gases that contribute to the
greenhouse effect which are the main cause of global
warming
➢ Deforestation: due to it only less amount of carbon
dioxide converted into oxygen which helps to rise the
temperature
➢ cattle: Methane release from cattle dung
➢ Agriculture: release 18% of total of greenhouse gases
➢ Livestock/domestic animals & meat production

Effect of global warming:

➢ It affects seasonal crops,
➢ Melting of polar ice

~ 19 ~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 19
 ➢ Adverse affect on human health & imbalance of
ecosystem.

GLOBAL ENERGY CONSUMPTION PATTERN & DEMANDS:

[GIVE A BRIEF ACCOUNT ON THE GLOBAL ENERGY
CONSUMPTION & DEMANDS?]
Amount of energy consumed by a country depends on the
living standard of its citizens & the degree of its
industrialization. The average energy required for a man to
maintain his daily activities require about 20 K calorie per day.
This energy is supplied by food he ate. In addition, Man uses
more energy for transportation, industrial & agricultural
activities. At present, the global energy consumption per
capital per day is about 2000 times the 20K calorie he needs
for maintaining life.
The main energy sources being used by us are coal, biomass,
nuclear energy, hydropower, mineral oil, natural gas , etc.
other energy required by the world is fulfilled by other energy
sources like solar energy, tidal energy , wind energy etc. The
present status of energy consumption (worlds):
Mineral oil= 37% coal=27%
Natural gas=14% Bio-fuel= 14%
Hydroelectricity=5% Nuclear energy=3%
From the data of 1900 to 2010: shows that the global energy
consumption rate is rapidly increasing.

~ 20 ~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 20
ENERGY CONSUMPTION SCENERIO IN NEPAL:
[GIVE AN ACCOUNT OF THE ENERGY CONSUMPTION
SCENERIO IN NEPAL?]
The use of energy is increasing in Nepal in Nepal every year.
The development efforts & rapid development of living
standards demand even increasing use of energy. However,
the conventional energy sources which are non-renewable
sources of energy are limited. In Nepal existing energy sources
are classified into two categories: Conventional & alternative
source of energy.
Nepal is not industrially developed country. So, the Biomass
energy source such as burning of wood, agricultural products
&animal waste products are the most important source of
energy in Nepal. Petroleum products such as petrol, diesel,
kerosene etc are the other energy sources used in Nepal.
Another major source of energy in Nepal is Hydropower.
According to the energy system planning & Analysis Centre for
Studies, T.U., the major energy consumption pattern in 2015 is
given below
Biomass=78% Electricity=3%
Coal=4% Petroleum=12%
Modern renewable energy=3%

OZONE HOLE:
The region in the Ozone layer where there is the deficiency of
Ozone (O3) is called ozone hole. A range number of such holes
have been found in the stratosphere. E.g. a large hole was

~ 21 ~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 21
reported over Antarctica where ozone content dropped by
30% from its normal value
When the ozone holes are created, the high frequency UV
radiations coming from outer space directly enter into the
stratosphere & cause adverse effect on the living organisms.

ROLE OF THE PHYSICS FOR THE DEVELOPMENT OF NATION:

[WRITE AN ESSAY ON THE ROLE OF PHYSICS IN THE
DEVELOPMENT OF A DEVELOPING COUNTRY LIKE NEPAL?]
In the 18th century, the hydro-energy brought revolution in
water transport in Britain, which helped it to establish itself as
one world. So we see that every fact required for the
development of a nation is based in the laws of Physics.
Physics & Society are complementary to each other. The use of
Physics with its proper study increases efficiency & confidence
in a physics work.
Hoping for the development of a nation without Physics is like
crying for the moon. Knowledge of Physics increases Efficiency,
Confident & make more realistic. Thus, they contribute much
to the Nation's social % Infrastructure development. So a
Nobel Laureate has rightly said" If you want to develop your
nation, you must give more priority to the study of Physics".

Following are importances for the development of the Nation:

Knowledge of Physics increases Efficiency, Confident & make
more realistic.
➢ Search & study of extra Terrestrial bodies have been made
possible for us by the study of Physics

~ 22 ~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 22
➢ Search of new technology for the development of the
societies is possible only by studying of Physics
➢ Study of environmental Physics creates awareness in
people towards importance of healthy environment
➢ All technology which have been facilitating our societies
are basically developed on the basis of laws of Physics
➢ Study of Physics helps us in keeping the nature in balance
condition.
➢ Knowing the laws of nature , our society can understand
how to live in harmony with the nature
➢ Being fundamental science, Physics is used in other
discipline of Science.

What is energy conservation & energy degradation?

The conservation of available energy sources for a present &
future is called energy conservation. Energy conservation
involves utilizing the existing energy sources, reusing &
recycling the energy forms & conserving them for the future.

Energy degradation is the uncontrolled exploitation (misuse) of

energy sources. Energy degradation involves polluting the
energy sources, using the energy randomly & uncontrollably.
Energy degradation has also contributed to the energy crisis in
the modern society.

COMMON POLLUTANTS:
➢ Deposited substances such as smoke ,dust, soot etc
➢ Gaseous substances like NO, NO2, SO2 , H2S,CO, Halogens.

~ 23 ~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 23
 ➢ Solid waste like plastics bags, piece of glass & metals
➢ Economic poisons like Herbicides, fungicides, insecticides
& other biocides
➢ Complex organic compounds like Benzene, ether, acetic
acid etc
➢ Fertilizers, Radioactive wastes, Noise, Heat etc

~ 24 ~ 1
Brij Kumar Singh, M.Sc Physics CDP, TU, Kirtipur Nepal Email: brijsingh707@gmail.com
Physics lecturer at Shree Secondary technical & vocational School, Dharapani, Dhanusha , Nepal
Former Physics Lecturer at Nepal Adarsha School/campus Syangja Waling Nepal
Former Secondary Science teacher at Everest Academy School, Lalbandi, Sarlahi 24