Civil Engineering

Roles of Civil Engineers for Society

Every action of engineering is directly related to societal issues, and hence engineers have an impact on society. By using engineering techniques in the meantime engineer helps to solve the societal problems.

Some of the basic roles of civil engineers for society are:

  1. Help and train people to operate and maintain the solution system for its sustainability.
  2. Regularly interact with society to understand the societal issues and propose a plan for the of short-medium-long term solutions.
  3. To provide technical support to the society.
  4. Solve the societal issues without compromise with the safety, and environmental options.
  5. To help in the decision-making process to choose the best option.
  6. For optimum design, including detailed specifications to implement the designed product.
  7. By technical supervising on the construction works.
  8. By providing training to the people to operate and maintain the constructed work.

How can an engineer help to change society?

Engineers can help society by bringing the following Changes:

  1. By lowering the cost of construction work.
  2. By maintaining the safety of workers as a site.
  3. By faster construction of the project.
  4. By increasing productivity.
  5. By maintaining the quality of work.

Also Read: Top Duties and responsibilities of a civil engineer

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What is Hard Water?

The water which gives low or no froth with soap and detergent is known as hard water. Hard water is due to the presence of bicarbonates, sulphates, chlorides, nitrates of calcium and magnesium.

Hard water is of two types

Temporary hardness: Temporary hardness of water is due to the presence of bicarbonate of calcium and magnesium in the water. It can be easily removed by simply boiling water. Calcium bicarbonate and magnesium bicarbonates are converted into carbonate forms which settle down.

                Ca(HCO3)2 ———> CaCO3 ↓ + H2O + CO2

              Mg(HCO3)2 ————> MgCO3  +   H2O   +  CO2

Permanent hardness: Permanent hardness is due to the presence of sulphate, chlorides, nitrates of calcium and magnesium. Such water can’t be removed by boiling and advanced methods are applied. First of all total hardness of water is determined by titrating with EDTA and then permanent hardness is determined by the same method. Temporary hardness is determined by subtracting the amount of permanent hardness from total hardness.

Determination of total hardness

Both temporary and permanent hardness of water is determined by complexometric titration using EDTA (ethylene diamine tetraacetate) as a complexing agent in the presence of the solochrome black T indicator.

For total hardness: For determination of total hardness of water, a sample of 50 ml cold water is titrated with EDTA by using solo chrome black T prepared in the basic buffer solution till wine red color changes into clear blue color.

S.N Vol. of water Vol. of EDTA(Burrette reading Concurrent reading
Initial Final Different
1 50 ml        
2 50 ml        
3 50 ml        

Effect of hard water

  1. Soap and detergents do not give froth properly.
  2. It corrodes water pipe, metallic pots
  3. It fads the color of clothes, mats, etc.
  4. Also, it affects and can damage the human body parts such as the kidney, liver.
Effect of Hard Water on tap
Effect of Hard Water On Water Tap Surface

Also Read: Chemical Oxygen Demand (COD) AND Dissolved Oxygen (DO)


Air pollution

Air pollution is the addition of poisonous gases like CO,  NO, NO2, SO3, SO2, O3, H2S dust, smoke and unburnt hydrocarbons like CH4,C2H5, CFC,  etc. produced by either natural phenomena or human activities in Earth’s atmoshpher. These gases are continuously released to the atmosphere day by day due to which air pollution occurs.

The air pollutants present in the atmosphere disturb the dynamic equilibrium in the atmosphere and thereby affect the earth habitats and their environment.

Sources of air pollution

There are several sources of air pollution which may be either natural process or man made activities such as

  1. Burning of coal, wood, and Oils
  2. Internal combustion of engines of car, buses, trucks,  trains, etc
  3. Chemical industries: various poisonous gases like CO,  NO, NO2, SO3, SO, etc are released
  4. Dust produced from heavy traffic and crowded population
  5. Carbon monoxide by combustion hydrocarbon, fuels, etc.
  6. volcanic Eruption, Wars, agricultural activities, scientific experiments, rocket launching, etc

Effect of air pollution

  1. Human being suffers from diseases like heart failure, lungs disease, and high blood pressure.
  2. It increases tension makes fatigue and restless.
  3. It may cause blindness, skin disease.etc
  4. A man may become senseless.

Methods of control

The prevention of the production of air pollutants is the core of the control of air pollution.

It can be control by the following methods

  1. By minimizing the production of by adding tetra ethylene lead in petrol.
  2. It can be controlled by using alternative sources of energy instead of fossil fuels.
  3. By planting green trees in rural as well as urban areas.
  4. It can be controlled by make awareness of air pollution
  5. By banning the use of low-quality gasoline.
  6. It can be controlled for the long term by lunching international and national programs for the protection of the atmosphere.

Also Read This: Chemical Oxygen Demand (COD) AND Dissolved Oxygen (DO)

Building Materials

Heat treatment of steel

Heat treatment (heat treating) is a process in which the desire mechanical properties of steel are achieved by heating it to a different temperature. There are many types of heat treatment processes for steel.

Types of Heat Treatment

A) Annealing

Annealing is a process of heating steel in which temperature generally above the critical temperature, holding it for a definite period of time and cooling it at a slow rate. While cooling the steel embed inside the ash, lime or sand-like non-conducting materials.

Types of Annealing:

  1. Full annealing:- In this process, the metal is first heated up to 500 degrees Celcius above the critical temperature and hold it for one to two hours. Then the steel is cooled slowly to obtain the desired micro-structure.
  2. Isothermal annealing:- In isothermal annealing process steel is heated as in full annealing and allowed to rapid cool up to the temperature at which the transformation is desired. Then the steel is held at the temperature necessary to complete the transformation.
  3. Sub critical annealing:- This type of annealing first steel is heated below the critical temperature and allowing it to cool after holding it for 2 to 4 hours. This is also called the process annealing.
  4. Spheroidization:- Steel is heated at or just below the lower critical temperature and holds for a sufficient period of time to form small spheroids, then cooling very slowly.

Importance or uses of Annealing

  1. To improve machine ability.
  2. To soften the steel by re-crystallization and refine the grain size.
  3. For the improve ductility and malleability.
  4. To relieve the internal stresses produced during forging, pressing, etc.
  5. To improve the electrical and magnetic properties of steel.
  6. For removing the entrapped air, blow holes, pipes, etc. formed during casting.
  7. To overcome other imperfection produced during plastic deformation.

B) Normalizing

Normalizing is the process of heat treatment in which steel is heated up to 50-degree temperature above the critical temperature and allowed to cool in still air. This process is used to improve the quality of cast, welded or forged steel. It is also used to improve the quality of over heated or non-uniformity heated steel.

Importance or Use of Normalizing:

  1. To end the coarse-grained structure obtained during forging, rolling, extrusion, etc.
  2. For the improvement of the strength of medium carbon steel.
  3. To improve the machinability of steel.
  4. To reduce the internal stresses etc.

Read this: Detail about steel bar and its composition

Hardening of steel

C) Quenching/hardening of steel

In Quenching or hardening of steel, the steel is heated above its critical temperature and then allowed to cool rapidly by plunging it into the liquid bath. This form the extremely hard needle-like structure known as martensite. Clearwater, salty water or oil is used as quenching media to obtain desired hardness. It not only increases the hardness and resistance against wearing but also decreases the toughness and increases brittleness.

D) Tempering

Tempering is the process of heating quenched steel to some predetermined temperature between room temperature and critical temperature, holding it for the time sufficient to transformation and then cooling it at a slow rate in air.

Steel, when allowed for quenching produces a highly hard structure known as martensite. Martensite is not only hard but also brittle and thus decreases toughness.

Importance or uses of tempering

  1. To increase the toughness and ductility.
  2. To decrease the hardness.
  3. To relieve the stress produced during quenching.

Read this: Differences between cast iron, wrought iron, mild steel, and hard steel

E) Surface hardening

Surface hardening is the process in which the outer surface of the steel is hardened and the core of the steel is only refined.

Different methods of surface hardening are

  1. Case hardening: It is the process at which steel is heated in presence of solid, liquid or gas which is rich in carbon content in order to enable the surface to be hardened while retaining a tough ductile core.
    • Different types or methods of Case hardening
      1. Pack hardening: In this process steel is kept inside a box and surrounded by carbon-rich compound and heated to a temperature of 9000C to 9200C, depending upon the composition of the steel. Then the steel is allowed to cool and removed from the box. Now, it is quenched in water or other suitable media.
      2. Liquid carburizing: In this process, the steel is plunged to molten salt containing carbon such as sodium cyanide. This produces a thin layer of hardened steel. Then the steel is quenched as in the case of pack hardening.
      3. Gas carburizing: This process is carried out by heating the steel in a furnace into which the gas which is rich in carbon such as methane, propane, etc are introduced. There should be a continuous flow of carburizing gas.
  2. Nitriding: This process of surface hardening is used for only special alloy steel and not for plain carbon steel. In this process, no carbon is used for hardening, but nitrogen gas is used. Nitrogen is introduced to the steel by passing ammonia gas through the furnace containing steel and heated to a temperature between 4800C to 5400C.
  3. Cyaniding: In this process, steel is heated in molten cyanide salt at about 8500C followed by quenching. Both carbon and nitrogen are absorbed in this process.
  4. Flame hardening: In this process, the part of the surface to be hardened is heated above the critical temperature by flame and quenched rapidly. It is used to harden the more wearing parts of the machine such as gear teeth.

In this way, the heat treatment of steel is done.

You may be searching for this: Detail about the formation of Cast iron

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Acid rain

Especially in the industrial areas, countries are suffered by the harmful acid rain. The atmosphere is polluted by different oxides of non metals like CO, CO2, NO, NO2, N2O5, SO2, SO3, P2O5, As2O3 etc produced from industries, factories. These non metallic oxides combine with water in the atmosphere to form acids and fall in the form of droplets on the earth surface which is called as acid rain.

Reactions of formation of acid rain from different non metallic oxides are

                      2NO + H2O→2HNO2 nitrous acid

                      2NO2   + H2O→HNO3   +  HNO2

                      SO2   + H2O→H2SO3 (sulphurous acid)

                       SO3  + H2O → H2SO4

                     P2O5  +  3H2O→2H3PO4 (ortho phosphoric acid)

                     CO2  + H2O → H2CO3 (carbonic acid)

 Effects of acid rain

 Acid raining is becoming more tremendous problem and challenge for coming generation. Developed industrial countries are affected badly till now but other countries will be victimized by acid rain very soon. Natural scenery, natural beauties, fertile lands, forests,grassy lands and artificial creations are going to be destroyed day by day.

Some of the adverse effects of acid rain are,

  1. It increases the acidity of soil which becomes unfit for crops production.
  2. It destroys forests, grassy lands and fertile lands.
  3. Causes stone leprosy.
  4. It destroys Buildings, marbles and wooden materials, statues and sculptures, Historical places etc.
  5. It corrodes metallic materials, pipes etc.
  6. Natural beauties like mountains, falls, rivers, coastal areas etc are destroyed.
  7. It disturbs the terrestrial, arboreal as well as aquatorial ecosystems.
  8. It causes sterility in animals, pieces, birds and retards production of vegetation.

  Control measures

  1. It can be controlled by applying alternative sources of energy instead of coal and gasoline.
  2. It can be controlled by banning of use of high fuel consuming vehicles, motor, lorry, vans.
  3. Can be controlled by removing old and low quality machine.
  4. It can be minimized by planting green trees on the road way sides and near industrial areas.
  5. It can be controlled by treating smoke of industries with suitable metals.
  6. World wide campaign of awareness must be run.

Water Pollution ll Sources and control Measures of water pollution

The state of deviation from the pure condition of water due to the mixing of foreign substances whereby its normal functions and properties are affected is known as water pollution. Populated water is harmful to animals and plants as well as unfit for domestic, industrial and agricultural uses.

The domestic wastes from rural and urban areas, sewage and garbage from industries, hotels, chemicals, and sludge of hospitals, industries, and factories are the major factors for water pollution.

Polluted water has any one or more of the following signs

  1. It has a bad taste to drink.
  2. It has an offensive odor.
  3. Also, it has an unpleasant color.
  4. There is an unchecked growth of weeds.                     
  5. It may have oil or grease floating on the surface.

Sources of water pollution

The main sources that are responsible for water pollution are

  1. Sewage and domestic wastes: It includes excreta of animals and human, dead and decay parts of animals and plants, sewage, sludge, soap, detergents, untreated municipal sewage, etc. Most of the parts of the wastes come from the cooking room. These all pollutants mix directly or indirectly to the source of water.
  2. Industrial effluents: It contains toxic materials, chemicals and hazardous compounds like aldehyde, ketones, phenols, cyanides, oils grease, dyes, acids, alkalies corrosive metals like Pb, Hg, Sb, etc from industries, hospitals, auto-work shop, laboratories, etc.
  3. Agricultural discharges: The residues of chemical fertilizers, pesticides, insecticide, and herbicides retain on the soil surface and dissolve in water due to which uncontrolled growth of weed occurs and ponds, lakes, etc are converted into grassy lands. Mixing of the residue of pesticides, fertilizers, insecticides to drinkable water causes diseases like dysentery, cholera, typhoid, etc.
  4. Thermal pollutants: Coal-fired or nuclear fuel-fired steam power plants are the sources of thermal pollution in which only a fraction of the heat is converted into useful works and the rest is wasted. The condenser of power plants are drained to water sources like river or lakes at a high temperature which decreases the D.O. of water and it adversely affects aquatic life.
  5. Siltation: it is the process of mixing of soil and rock particles into water. It is a serious problem for the hilly region. It is mainly due to flooding and soil erosion.
  6. Radioactive materials:  Different human activities like mining and processing of ores to produce radioactive substances, uses of radioactive weapons, use of radioactive materials in power plants and uses of radioactive isotopes in medical, industries and research works are the main sources of radioactive materials.

What are the pollutants of water pollution ?

Types of water pollutants

According to nature and compositions, water pollutants are of following types

  1. Inorganic pollutants: It includes a broad range of pollutants such as acids and bases like HNO3, HCl, NaOH, Ca(OH)2, NH3, etc soluble salts like carbonates, acetates, nitrates, sulphates, bicarbonate, etc and inorganic pesticides.
  2. Organic pollutants: It includes oxygen demanding wastes, plant nutrients, sewage, synthetic organic compounds, fats, and oils.
  3. Sediments: They are the most extensive pollutants of surface water and are produced by soil erosion, flooding, agricultural and construction activity.
  4. Radioactive materials: Different human activities like mining and processing of ores to produce radioactive substances, uses of radioactive weapons, use of radioactive materials in power plants and uses of radioactive isotopes in medical, industries and research works are the main sources of radioactive materials.

Why to control water pollution?

Because of the following reasons, if you don’t aware and move forward to control it. Then one day you will be the victim of water pollution.

Water is the most interrelated substance with living things and humans. So its pollution can cause immense harm to public health. Some effects of water pollution are immediately recognized while others are only reflected after months or year later. Some effects of water pollutions are given here,

  1. Spread of infectious diseases: Water is the carrier of pathogenic micro-organisms and can cause adverse effects on public health. The water-borne diseases like typhoid, paratyphoid fever, dysentery, cholera, polio, etc. different skin diseases, poor blood circulation, etc are the main problem of polluted water.
  2.  Destroy of the aquatic ecosystem: sewage and runoff (fertilizers) from agricultural lands provide nutrients to the algae, weeds in the bottom of water sources and increase the overgrowth of the plants which cover the pond, lake and finally they turn in to grassy lands. The growth of plants in the water source causes the D.O.
  3. Destroy of aquatic life: Residue of pesticides, herbicides, toxic, oils, acid, and alkaline chemicals directly affect the aquatic life. It causes a decrease in D. O. Such pollutants to retard the breeding rates and damage the plants and animals.
  4. Damage of property of water: Pollutants destroy the natural properties of water. It causes acidity, turbidity, alkalinity and increases the temperature of the water.
  5. Contamination of marine food sources: Marine foodstuff is contaminated by polluted water which ultimately affects human health.

Control measures of Water Pollution

  1. The wastes from industries, factories, pharmaceuticals, and hospitals must be managed properly.
  2. Most of the wastes must be preceded for recycling.
  3. Sufficient and accessible dumping sites must be managed in rural and urban areas.
  4. Public awareness campaigned should be launched by central as well as local authorities.
  5. Sewage, industrial wastes should be preceded for aerobic and anaerobic treatment.

Soil Pollution and its effects

The contamination of soil with acid rain, fertilizer, insecticide and pesticide residue, metals like Pb from exhausted petrol, sulphate, nitrates, etc is known as soil pollution. Soil is the acceptor of large quantities of waste products that may be a domestic, human, animal, industrial and agricultural.

The combustion of sulphur containing fuels emits SO2 and finally leaves sulphate on the soil. Fertilizers, pesticides, insecticides, herbicides applied to the crops are largely retained by the soil. Industrial products such as plastics, rubbers, glasses, tin and similarly toxic wastes like waste oil, lubricants, acid tars, lacquers, etc are deposited on the soil. Such pollutants destroy soil quality.

Sources of soil pollution

  1. Industrial products: large percentage about 15.2% of pollutants includes from industrial productions like rubber, plastics, toxic substances, chemicals, sewage, glasses, dust, waste oil, paints, decay row materials, etc directly mix into sources of water and spread over fertile land through irrigation
  2. Agricultural: Residues of pesticides, herbicides and unconsumed fertilizers largely retained by the soil surface day by day due to their heavy use. After a certain year, fertile lands are converting into sterile and become bare land which causes land slide, flooding, soil erosion, etc.
  3. Domestic: It includes the garbage from houses and other premises such as un-degradable domestic wastes like containers, pieces of bottles, plastics, glasses, gasoline, polythene, etc. Such domestic pollutants take a large part in the pollution of soil in developing countries like Nepal. There are no safe and accessible dumping sites as well as strict rules-regulation by the government. So, domestics pollutant is not controlling and managed in our country due to which as a result soil is pollution is increasing rapidly. About 8.5% soil pollutants are from domestic and trade.
  4. Volcanic eruption: Metallic oxides, sulphate residues, and other tarry liquids. Solid tarry matters are spread over the soil surface and cover a large areas.
  5. Mining and quarrying: It contains about 67% soil pollutants like rock particles, heap of wastes from quarries and tarry liquids like seam of coal, acid tars, waste oil, etc from mining.
  6. Toxic substances: Tarry liquids, Pb containing gasoline sludge, water-kerosene mixture, acid tars, bases and cyanide wastes. Different organic solvent etc are toxic matters
  7. Construction: Various construction works such as the construction of roads, buildings, tunnels, bridges, etc are the sources of the soil pollutants. Construction work consists about 2% pollutants.

Effects of Soil Pollution

  1. It destroys the fertile land
  2. Affect the health of people through fruits ,vegetables and crops
  3. Decreases the production rate of crops, grains.
  4. It causes soil erosion and flooding.
  5. It direct effect habitats of human, forest, grassy lands and hilly regions.

Controls measure of soil pollution

  1. By replacing use of insecticides, fungicides by biological methods of control.
  2. Controlled by advising and applying manure rather the use of chemical fertilizers.
  3. By dumping domestic, industrial and chemicals.
  4. By advising to apply lead free gasoline
  5. Controlled by recycling the domestic materials.

Things taken in account for load analysis of a Building

In the mind of fresh out engineers or those who didn’t work on the field of building, it may come out how we can analyze the seismic and structural load of a building.

What important points are taken into account before designing an earthquake resistance building analysis etc?

What is seismic analysis in a building?

 It is the calculation of the response of a building structure to the earthquake.

What is Structural analysis in a building?

It is the determination of the effects of loads on building structures and their components on it.

What is the objective of the analysis of loads on the building?

  1. Estimation of dead loads, live loads, earthquake load( for beam, slab, columns, staircase, foundation, roofing for the safety of a building.
  2. Analysis and design of building for normal and earthquake load.
  3. To prepare the architectural drawing in terms of earthquake load.
  4. For the preliminary design to checking of structural members.
  5. For preparing the structural drawing.
  6. Drawing and detailing of reinforcement bars according to design data and ductility criteria
  7. Preparation of cost estimation.

Why analysis of building is necessary?

The analysis of building is necessary because it is more useful with rapid urbanization and lack of construction space. In the earthquake-prone zone, Seismic analysis will be compulsory for the construction of building in the future.

Reference Codes For building Analysis: 
  1. Nepal National  Building Code(NBC 000-1994) (For Nepal only)
  2. Indian Standard (IS) codes
  3. IS 456: 2000 Plain and Reinforced Concrete- Code of practice
  4. IS 875:1987 (Reaffirmed 1997) Code of Practice for Design Loads (Other)
  5. IS 1893(part I): 2002 Criteria for Earthquake Resistant Design of Structures
  6. Bureau of Indian Standards Special Publication
  7. Design Aids for Reinforced Concrete to IS 46-1978
  8. SP 22: Explanatory Handbook on Codes for Earthquake Engineering (IS 1893:1975 and IS 4326:1976)
  9. SP 24: Explanatory Handbook on Indian Standard Code of Practice for Plain and Reinforced Concrete IS 456;1978
  10. SP 34: Handbook on Concrete Reinforcement and Detailing
  11. Textbook on RCC Design, Earthquake, Engineering and other books.

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Question Paper

Pokhara University Old Question Paper Collection

Hello, Pokhara University Students !!!

We have a collection of old question papers from 2005 to 2019. We frequently update the new question paper.

From 2005 to 2015 we have a collection of all engineering program question papers.

Later from 2016 to 2019, we have the only collection of the civil engineering branch.

Download Complete Question Paper Of Pokhara University of All engineering faculty from 2005 to 2015.

A Complete Collection of Spring and Fall Question Paper.

Pokhara University

Latest Question paper up to 2019 Civil Engineering. 

Latest Question paper up to 2016 Civil Engineering. 

 2005 Fall Question Paper Collection [wpdm_package id=’11075′]

2011 Fall Question Paper Collection Download

2012 Spring Question Paper Collection Download

2013 Fall Question Paper Collection Download

2013 Spring Question Paper Collection Download

2014 Fall Question Paper Collection Download

2014-Spring-Question Paper Collection Download

2015 Fall Question Paper Collection Download

Note: From 2005 to 2015 we have complete collection every engineering branch old question paper. Later on, we have the only collection of old question papers of civil engineering.

If you have any old question collection please feel free to share with us because your collection may help others.

Are you seeking for Syllabus of Pokhara University:

Pokhara University Civil Engineering Syllabus (BE. Civil)

For more info about Pokhara University Visit Official Site Click Here.

Science And Technology

Ozone layer depletion and CFC

Ozone layer serves as a protective umbrella to save the living being on the earth from danger radiations like ultraviolet rays, cosmic rays. Ozone layer is a natural gift for living creatures offered by nature. But it is being destroyed by the production of greenhouse gases like CO2, CO, NO, NO2, SO2, SO3, CH4, C2H6, CFC, etc due to human activities such as industrialization, deforestation, combustion of coal, diesel, wood and scientific research.

These gases diffuse from earths surface forming a hazy layer to the stratosphere region where they react with ozone and make a hole in the ozone layer. The phenomenon formation of a hole in the ozone layer by destroying it with greenhouse gases like NO2, SO2, SO3, CO2, CO, NO, NO2, CH4, C2H6, CFC is known as ozone layer depletion.

In 1958, NASA scientists observed a hole in the ozone layer over Antarctica and it has been found that the ozone layer is depleting at an alarming rate. Although all greenhouse gases are partially responsible for the depletion of the ozone layer, the main culprits are CFCs i.e. chlorofluorocarbon or Freon’s which is extremely stable, non-corrosive and inert compounds. It is thought that one molecule of CFC has capability to destroy one lakh molecules of ozone (O3).

The probable mechanism of ozone layer depletion is;

         CFCl3 ————> CFCl2˚ + Cl˚

         Cl˚   + O3 ————-> ClO˚ + O2

             ClO˚ + O ————-> Cl˚ + O2

The reaction goes on utill the ability to destroying by ClO˚ ion is ceased.

Effect of Ozone layer depletion      

The effects of ozone layer deflection are

  1. The UV rays directly reach to the earth and affect the living being on the earth.
  2. It causes global warming due to the heating effect of UV light.
  3. It destroys the green plants and small creatures.
  4. It can burn skin and causes blindness.
  5. It decreases the fertility rate and resists the growth.
  6. It destroys fertile land and decreases crop productions.

Controls measures

It can be controlled by

  1. CFC producing refrigerator, spray can, air condenser should be prohibited.
  2. Combustion of fossil fuel, plastic and diesel should be diminished.
  3. Bombarding should be controlled.
  4. People should be given the knowledge ozone layer.


At the first time CFCs were considered as a miracle chemicals because of the non-reactive, non-toxic, non-inflammable and stable nature of CFCs. They were used as coolant in the refrigerators, air conditioners, spray can etc for long time.

But later, it has been found that CFCs are the major culprit for the ozone depletion. Therefore, now a day, the use of CFC is replacing by other molecules like ammonia as a coolant. CFCs are released by the operation of such refrigerants, aerosol can, burning of plastics, hydrocarbons and diffuses to the stratosphere. In the stratosphere, CFCs react with ozone molecules.

Since CFCs are extremely stable and nonreactive, they can persist for a long time and diffuse into stratosphere where they get dissociated by ultraviolet radiations.

It is believed that one molecule of CFC can destroy one lakh molecules of O3 continuous which forms the hole in the ozone layer.

The probable reaction is 

         CFCl3 ——-> CFCl2˚ + Cl˚

         Cl˚  + O3 ———> ClO˚ + O2

           ClO˚ + O ——-> Cl˚ + O2

The reaction goes on till the ability of destroying by ClO˚ ion is ceased

Effects of CFC

  1. Depletes the ozone layer due to which UV rays reach the earth.
  2. It causes global warming.
  3. It invites the destruction of living being due to enter of UV rays.

Controls measures

  1. CFCs must not be used in cooler, air condenser
  2. Plastic should not be burnt but recycled.
  3. CFC producing appliances must be banned.
  4. It can be controlled by making awareness about the effect of CFC.

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Electricity – Production, Transmission, and Distribution in Modern Society.

Electricity is the term of energy and with the development of civilization, necessity and importance of energy increased. Among different forms of energy, electricity is one of the basic and fundamental forms of energy that has been an invincible part of our modern society.

And now at the present time, electricity cannot be taken out separately from the list of our basic needs.

Is Electricity Is Our Basic Need?

There are lots of things to show off the importance of urban areas. But where we are living in rural areas might not visually find much usage of electricity. But there is. Whatever we find around us form toothbrush, toothpaste, shoes, books, food, clothes, furniture, etc. everything is the part of the industrialization of which electricity is the first priority.

Similarly, electricity has lots of importance in our daily life too. In the morning, to get up we set up an alarm on our mobile phone or portable watch.

If it is winter we use the heater and in summer, we need a fan to cool ourselves, and when the sun is about to set we need to light our home, and the gadgets like mobile phones, watch and laptops, all need electricity to run. In the absence of electricity, they will run out of battery. If we keep our step out of our home, the vehicles use electricity.

If we are in the office, we need electricity to use or a computer, photocopy machine, etc. And we move from village to city areas, when people get up they use an electric toothbrush, water heater to take shower, vacuum cleaner to clean their room and washing machines to wash their clothes, and so far from smallest to largest scale industries all need electricity to start and keep running.

As a conclusion, in today’s modern world, our life becomes inoperable without electricity and since it is the basic thing for other developments like communication, transportation, industrialization, education, health, etc. It is the fundamental infrastructure of development.

Source of electrical energy

Sources of energy are divided into two different parts from which electricity can be generated.

Thermal (Heat emitting) Thermal (Heat emitting)
Coal, Nuclear fission,          Solar, tidal
Geothermal (Heat of Earth)       Wind, Hydropower

Production of Electricity

Generally, electricity is generated by hydropower. In this system, the water of the river is collected in a dam in order to filter the water and give it potential so that it can be systematically used for the generation of electricity.

  • Water collected in a dam is then allowed to flow at high speed to the turbines.
  • The kinetic energy of the water makes the turbines rotate.
  • Then the mechanical energy is converted into electrical by generators connected to the turbines.
  • And the generated electrical power is collected in the national grid.
  • The national grid is the storehouse of the country’s hydropower energy.

Transmission of Electricity

Electricity Station

The hydropower energy stored in the National Grid is then transmitted by the high tension line. A high tension line carries a very high voltage of electrical energy. The three lines of high tension transmission are called Blue line, Yellow line, and Redline. Electricity cannot be used directly from a high tension line for the general-purpose since this contains a very high voltage of current.

Distribution of Electricity

Since electricity cannot be distributed high tension lines for normal purposes. Step-down transformers shall be in distribution areas to distribute the electricity for normal use. The step-down transformer converts high voltage current to lower potential thus used to convert high tension transmission to low voltage phase and neutral line and finally distributed for home and office use.

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Download Engineering Drawing notes

An engineering drawing is a technical drawing, which is used to fully and clearly define requirements for engineered items. More than merely the drawing of pictures, it is also a language—a graphical language that communicates ideas and information from one mind to another.
Source: Wikipedia

A Complete Engineering Drawing Note For

Bachelor Of Civil Engineering.

Download Engineering Drawing Notes

Chapter 01 Introduction


Chapter 02 Using Drawing Tools


Chapter 03 Orthographic Projection


Chapter 04 Orthographic writing


Chapter 05 Pictorial sketching


Chapter 06 Orthographic Reading


Chapter 07 Dimensioning


Chapter 08 Orthographic Convention


Chapter 09 Section


Chapter 10 Convention in section


Chapter 11 Thread Fastener


Chapter 12 Working Drawing


Chapter 13 Roles of Engineering Drawing


Sectioning and projection of points, lines, and planes


Note: All Files are in power points

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