WHAT IS CONDUCTION? | Conductor And Non Conductor | Examples of Conductors

CONDUCTION

                         CONDUCTION:    The handle of metal spoon held in hot water soon gets warm. But in case of wooden spoon, the handle does not get warm. Both the materials behave differently regarding the transfer of heat. Both metals and non-metals conduct heat. Metal are generally better conductor than non-metal.

                        In solids, atoms and molecules are packed close together as shown in fig bellow. They continue to vibrate about their mean position. What happens when one of its ends is heated? The atoms or molecules Present at that end begin to vibrate more rapidly. They also collide with their neighboring atoms or molecules. In doing so, they pass some of their energy to neighboring atoms or molecules during collisions with them with the increase in their vibrations. These atoms or molecules in turn pass on a part of the energy to their neighboring particles. In this way some heat reaches the other parts of the solids. This is a slow process and very small transfer of heat takes place from hot to cold parts in solids.

                          How does these heat flow from hot to cold parts in metal so rapidly then non-metal? These free electrons move with high velocities within the metal objects. They carry energy at very fast rate from hot to cold part of the object as they move. Thus, heat reaches the cold parts of the metal object from its hot part much more quickly than non-metals.

                           The mode of transfer of heat by vibrating atoms and free electrons in solids from hot to cold part of body  is called conduction of heat.

                             All metals are good conductor of heat. The substances through which heat does not conduct easily are called bad conductor of insulators. Wood, cork, cotton, wool, glass, rubber, etc. are bad conductor or insulators.

THERMAL CONDUCTIVITY 

            Conduction of heat occurs at different rates in different materials. In metals, heat flows rapidly as compares such as wood or rubber as compare to insulator consider a solid block as shown in fig bellow. One of two opposite faces each of cross-sectional area.

            The amount of heat that flows in unit time is called the rate of flow of heat.

         Thus,

                                          Rate of flow of heat = Q / t

            

           It is observe that the rate at which heat flow through a solid object depends upon various factors.

CROSS - SECTIONAL AREA OF THE SOLID

           Large cross - sectional area A of a solid contains large number of molecules and free electrons on each layer parallel to its cross-sectional area and hence greater will be the rate of flow of heat through the solid. Thus 

                Rate of flow of heat     Q / t ∝ A

LENGTH OF THE SOLID

           Larger is the length between the hot and cold end of the solid , more time it will take to conduct heat to the colder end and smaller will be the rate of flow of heat. Thus

                 Rate of flow of heat Q / t ∝ 1 / L

TEMPERATURE DIFFERENCE BETWEEN ENDS

          Greater is the temperature difference T1 - T2 between hot and cold faces of the solid, greater will be the rate of flow of heat. Thus

                      Rate of flow of heat Q / t ∝ (T1 - T2)

     Combining the above factors, We get

                                                   Q / t ∝ A(T1 - T2) / L

    

     Rate of flow of heat Q / t = K A (T1 - T2) / L

             Here K is proportionality consent called the thermal conductivity of the solid. Its value depends on the nature of the substance and is different for different materials.

                                                    K = Q / t × L / A(T1 - T2)

              

             Thus, thermal conductivity of a substance can be defined as:

           The rate of flow of heat across the opposite face of meter cube of the substance to maintained at a temperature difference of one Kelvin is called the thermal conductivity of that substance.

USE OF CONDUCTOR AND NON CONDUCTOR

           In houses, good thermal insulation means lower competition of fuel. For this , following measures may be taken to save energy.

• Hot water tanks are insulated by plastic or foam lagging.
• Wall cavities are filled with plastic foam or wool.
• ceiling of rooms is covered by insulating materials.
• Double glazed window panes are used. These window panes have air between glass sheets that provides good insulation. 

Good conductor are used when quick transfer of heat is required through a body. Thus cookers, cooking plate, boiler, radiators and condensers of refrigerators etc. are made of metals such as aluminum and copper. Similarly, metal boxes are used for making ice, ice cream, etc.

WHAT IS THERMAL EXPANSION? - (Part 2)

THERMAL EXPANSION

THERMAL EXPANSION: You can know read the second part of thermal expansion if you want to read thermal expansion from start then go to (part 1)

CONSEQUENCE OF THERMAL EXPANSION 

                Why gaps are left in railway tracks? The expansion of solid may damage the bridge, railway tracks and rods as they are constantly subjected to temperature changes. So provision is made during contraction for expansion and contraction with temperature. For example, railway tracks buckled on a hot summer day due to expansion if gaps are not left between sections.

   

     Bridges are made of steel girders also expand during the day and contract during night. They will bend if their ends are fixed. To allow thermal expansion, one end is fixed wile the other end of the girder resets on rollers in the gap left for expansion. Overhead transmission lines are also given a certain amount of sag so that they can contract in winter without snapping.

APPLICATION OF THE THERMAL EXPANSION

 Thermal expansion  is used in our daily life. In thermometers, thermal expansion is used in temperature measurements. To open the cap of the bottle that is tight enough, immerse it in hot water for a minute or so. Metal cap expands and becomes loose. It would be easy to turn it to open.

      

   To join steel plates tightly together, red hot rivets are forced through holes in the plates as shown bellow. The ends of the hot rivet is then hammered. On cooling, the rivets contact and bring the plates tightly gripped.

    

   Iron rims are fixed on wooden wheels of carts. Iron rims are heated. Thermal expansion allows them to slip over the wooden wheel. Water is poured on it to cool. The rim contracts and becomes tight over the wheel.

BI METAL STRIP 

 A bi-metal strip consist of two thin strips of different metals such as brass and iron join together. On heating the strip, brass expand more than iron. This unequal expansion causes bending of the strip as shown in fig bellow.

  

  Bi metal strips are used for various purposes. Bi metal thermometer are used to measure temperatures especially in furnaces and ovens. bi metal strips are also used in thermostat switch that is used to control the temperature of heater coil in an electric iron.

THERMAL EXPANSION OF LIQUIDS

  The molecules of liquid are free to move in all direction with in the liquid. On heating a liquid, the average amplitude of vibration of its molecules increases. The molecules push each other and need more space to occupy. This accounts for the expansion of the liquid when heated. The thermal expansion in liquids is greater than solids due to the weak forces between their molecules. Therefore, the coefficient of volume expansion of liquids is greater than solids.

       

       Liquid have no definite shape of their own. A liquid always attains shape of the container in which it is poured. Therefore, when a liquid is heated, both liquid and the container undergo a change in their volume. Thus, their are two types of thermal volume expansion for liquid.

• Apparent volume expansion
• Real volume expansion

WHAT IS THERMAL EXPANSION? - (Part 1)

THERMAL EXPANSION 

 THERMAL EXPANSION: Most of the substance solid, liquid, and gasses expand heating and contact on cooling. Their thermal expansion and contractions are usually small and are not noticeable. However, these expansions and constructions are important in our daily life.

        The kinetic energy of the molecules of an object depends on its temperature. The molecules of a solid vibrate with large amplitude at high temperature than at low temperature. Thus, on heating, the amplitude of vibration of the atoms or molecules of an object increases. They push one another farther away as the amplitude of vibration increases. Thermal expansion result an increase in length, breadth and thickness of a substance.

LINEAR THERMAL EXPANSION IN SOLID 

  It has been observed that solids expand on heating and their expansion is nearly uniform over a wide range of temperature. Consider a metal rod of length Lo at certain temperature To. Let its length on heating to a temperature T becomes L. Thus

                Increases in length of the rod = ΔL = L - Lo

                     Increases in temperature         = ΔT = T - To

  It is found that changes in length ΔL of a solid of a solid is directly proportional to its original length Lo, and the changes in temperature ΔT. That is ;

               

                                            ΔL ∝ LoΔT

                                 or

                                            ΔL = α LoΔT ..............................(1)

                                 or

                                           L - Lo =  α LoΔT

                                 or

                                              L  = Lo (1 + αΔT) ...........................(2)

           

      Where α is called coefficient of linear thermal expansion of the substance.

        Know from equation (1), we get

                    

                                               α   =  ΔL / Lo ΔT ...................................(3)

         Thus, we can define the coefficient of linear expansion a α substance as the fractional increase in its length per kelvin rise in temperature.

VOLUME THERMAL EXPANSION 

    The volume of a solid also changes with the change in temperature is called volume thermal expansion or cubical thermal expansion. Consider a solid of initial volume Vo at certain temperature To. On heating the solid to a temperature T, let its volume becomes V, then 

                        Changes in temperature of a solid  ΔT    =   T - To

            And

                        Changes in the volume  ΔV                    =   V - Vo

     Like linear expansion, The changes in the volume ΔV is found to be proportional to its original volume Vo and changes in temperature  ΔT. Thus

                                            ΔV  ∝  VoΔT

                   Or

                                           ΔV   =  βVoΔT ................................... (4)

                                      V - Vo   =  βVoΔT

                                            V    =  Vo (1 + βΔT) .............................(5)

Where β is the temperature coefficient of volume expansion. by using equation (4), we get

                                             β   =  ΔV / VoΔT

 Thus, we can define the temperature coefficient of volume expansion β as the fractional change in its volume per kelvin change in temperature. The coefficient of linear expansion are related by the linear equation:

                                             β  = 3 α .................................... (6)

To be continue reading please go to next page to read more about Thermal expansion.

What Is The Evaporation?

The Evaporation

Evaporation: Take some water in dish. The water in the dish will disappear after some time. It is because the molecules of water are in constant motion and possess kinetic energy. Fast moving molecules escape out from the surface of water and goes into atmosphere. This is called evaporation.

"Evaporation is the changing in liquid into vapors (Gaseous state) from the surface of the liquid without heating it".

Unlike boiling, evaporation takes place at all temperature but only from the surface of the liquid. The process of boiling takes place at a certain fixed temperature which is the boiling point of that liquid. At boiling point, a liquid change into vapors not only from the surface but also with in the liquid. These vapors comes out of the boiling liquid as bulbs which breakdown on reaching the surface.

Evaporation play an important role in our daily life. Wet clothes dry up rapidly when spread. Evaporation causes coiling. Why? During evaporation fast moving molecules escape out from the surface of the liquid. Molecules that have lower kinetic energies are left behind. This lower the average kinetic energy of the liquid molecules and the temperature of the liquid. Since temperature of the substance depends on the average kinetic energy of its molecules. Evaporation of perspiration helps to cool our bodies.

  Evaporation takes place at all temperature from the surface of liquid. The rate of evaporation is affected by various factors.

TEMPERATURE

Why wet clothes dry up more quickly in summer than in winter? At higher temperature, more molecules of liquid are moving with high velocities. Thus, more molecules escape from its surface. Thus, evaporation is faster at high temperature than at low temperature.

SURFACE AREA

Why water evaporates faster when spread over large area? Large is the surface area of a liquid, greater number of molecules  has the chance to escape from its surface.

WIND

Wind blowing over the surface of liquid sweeps away the liquid molecules that have just escaped out. This increases the chance for more liquid molecules to escape out.

NATURE OF THE LIQUID

Does spirit and water evaporate at the same weight? Liquids differ in the rate at which they evaporate. Spread a few drops of ether or spirit on your palm. You feel cold, why?

What is thermometer?

THERMOMETER

 Thermometer: A device that is used to measure the temperature of a body is called thermometer. Some substance have property that changes with temperature. Substance that show changes with temperature can be used as a thermometric material. For example, some substance expand on heating, some changes there colors, some changes there electric resistance, etc. Nearly all these substance expand on heating. Liquids also expand on heating and are suitable as thermometric materials. Common thermometer are generally made using some suit able liquid as thermometric material. A thermometric liquid should have the following properties:

• It should be visible.
• it should have uniform thermal expansion.
• It should have a low freezing point.
• It should have a high boiling point.
• It should not wet glass.
• It should be a good conductor of heat.
• It should have a small specific heat capacity.

Liquid-IN-GLASS THERMOMETER

A liquid-in-glass thermometer has a bulb with a long capillary tube of uniform and fine bore such as shown in fig bellow. A dutiable liquid filled in the bulb. When the bulb contacts a hot object, the liquid in it expands and rises in the tube. The glass steam of a thermometer is thick and acts as a cylindrical lens. This makes it easy to see the liquid level in the glass tube.

Mercury freezes at-39 degree Celsius and boils at 357 degree Celsius. It has all the thermometric properties that is listed above. Thus, mercury is one of the most of the thermometric  material. Mercury-in-glass thermometer are widely used in laboratories, Clinics and houses to measure temperature in the range from -10 degree Celsius to 150 degree Celsius.

LOWER AND UPPER FIXED POINTS

A thermometer has a scale on its stem. This scale has to fixed points. The lower fixed point is mark to show the position of liquid in the thermometer when it is placed in ice. Similarly, upper fixed point is marked to show the position of liquid in the thermometer when it is placed in the steam at standard pressure above boiling water.

SCALE OF TEMPERATURE

A scale is marked on the thermometer. The temperature of a body is in contact with the thermometer can be read on that scale. Know a days digital thermometer is also used. Three scales of temperature are in common use. These are:

1. Celsius scale or centigrade scale
2. Fahrenheit scale
3. Kelvin scale

               On Celsius scale, the interval between lower and upper fixed points is divided into 100 equal parts as shown in fig bellow. The lower fixed point is marked as 0 degree Celsius and the upper fixed point is marked as 100 degree Celsius.

                

            On Fahrenheit scale, the interval between lower and upper fixed points is divided into 180 equal parts as shown in fig bellow. The lower fixed point is marked as 32 degree Fahrenheit and the upper fixed point is marked as 212 degree Fahrenheit.

           In SI units, the unit of temperature is Kelvin (K) and its scale is called kelvin scale of temperature as shown in fig. The interval between the upper and the lower fixed point is divided into 100 equal parts. Thus a changes in 1 degree Celsius is equal to change of 1 K. The lower fixed point on this scale corresponded to 273 K. The zero on this scale is called absolute zero and is equal to - 273 degree Celsius. 

CONVERSION OF TEMPERATURE FROM ONE
SCALE INTO OTHER TEMPERATURE SCALE

FROM CELSIUS TO KELVIN SCALE

    The temperature T on Kelvin scale can be obtained by adding 273 in the temperature C on Celsius scale. Thus

                             T (K) = 273 + C ............................. (1)

FROM KELVIN TO CELSIUS SCALE

   The temperature on Celsius scale can be found by subtracting 273 from the temperature in Kelvin scale. Thus

                             C = T (K) - 273................................. (2)

FROM CELSIUS TO FAHRENHEIT SCALE

     Since 100 division on Celsius scale are equal to 180 division on Fahrenheit scale. Therefore, each decision on Celsius scale is equal to 1.8 division on Fahrenheit scale. Moreover, 0 degree Celsius Corresponds to 32 degree Fahrenheit.

                      F = 1.8 C + 32 ................................... (3)

Here F is the temperature on Fahrenheit scale and C is the temperature on Celsius scale.

FROM FAHRENHEIT TO CELSIUS SCALE

 From equation (3), we can find the temperature on Celsius scale from Fahrenheit scale.

What is Atmospheric Pressure?

ATMOSPHERIC PRESSURE

Atmospheric Pressure: The earth is surrounded by a cover of air called atmospheric. It extend to few hundred kilometers above sea level. Just as certain sea creatures live at the bottom of ocean, we live at the bottom of a huge ocean of air. Air is mixture of gasses. The density of air in the atmosphere is not uniform. It decreases continuously as we go up.

Atmospheric pressure acts in all directions. A balloon expand as we fill air into it. In what direction does the balloon expand? The fact that atmosphere exerts pressure can be explain by simple experiment.

EXPERIMENT 

Take an empty thin can with  a lid. Open its can and put some water in it. Place it over flame. Wait till water being to boil and the steam expels the air out of the can. Move it from the flame, close the can firmly by its cap. Know place the can under the tap water. The can will squeeze due to atmospheric pressure. Why?

When the can is cooled by tap water, the steam in it condenses. As the steam changes into water, it leaves an empty space behind it. This lowers the pressure inside the can as compared to the atmospheric pressure outside the can. This will cause the can to collapse from all direction. This experiment shows that atmosphere exerts pressure in all directions. The fact can also be demonstrated by collapsing of an empty plastic bottle when air is sucked out of it.

MEASURING ATMOSPHERIC PRESSURE

At sea level, the atmospheric pressure is about 101,300 Pa or 101,300 N/m2 . The instrument that measuring atmospheric pressure are called barometer. One of the simple barometer is mercury barometer. It consist of a glass tube 1m long closed at one end. After filling it with mercury, it is inverted in mercury through. Mercury in the tube descends and stooped at a certain height. The column of the mercury held in the tube exerts pressure as it base. At sea level the height of the mercury column above the mercury in the trough is found to be about 76 cm. 

        Pressure exerted by 76 cm of mercury column is nearly 101,300 Pa equal to atmospheric pressure. It is common to express atmospheric pressure in terms of height of mercury column. As the atmospheric pressure at a place does not remain constant, hence, the height of mercury column also varies with atmospheric pressure.

        Mercury is 13.6 time is denser than water. Atmospheric pressure can hold vertical column of water about 13.6 times the height of mercury column at a place. Thus, at sea level, vertical  height of water column would be 0.76 m * 13.6 = 10.34 m. Thus a glass tube is more than 10 m long is required to make a water barometer.

VARIATION IN ATMOSPHERIC PRESSURE

         The atmospheric pressure decreases as we go up. The atmospheric pressure on mountain is lower than at sea level. At a height of about 30 km, the atmospheric pressure becomes only 7 mm of mercury which is approximately 1000 Pa. It would become zero at an attitude where there is no air. Thus, we can determine the attitude of place by knowing the atmospheric pressure at the place. Atmospheric pressure may also indicate a change in the weather. On a hot day, air above the Earth becomes hot and expends. This called a falls of atmospheric pressure in that region. 

         The changes in atmospheric pressure at a certain place indicate the expected changes in the weather conditions of that place. For example, a gradual and average drop in atmospheric pressure mean a low pressure in a neighbor locality. Minor but rapid fall in atmospheric pressure indicates a windy and showery condition in the nearby region. A decrease in atmospheric pressure is accompanied by breeze and rain. Whereas a sudden fall in atmospheric pressure often followed by storm, rain and typhoon to occur in few hours time.

        On the other hand, an increasing atmospheric pressure with a decline later on predicts an intense weather conditions. A gradual large increase in the atmospheric pressure indicates a long spell of pleasant weather. A rapid increase in the atmospheric pressure mean it will soon be followed by a decrease in the atmospheric pressure indicating a power weather ahead. 

KINETIC MOLECULAR MODEL OF MATTER

Kinetic Molecular Model Of Matter

 The kinetic molecular model matter has some important features. These are

• Matter is made up of particles called molecules.
• The molecules remain in continuous motion.
• Molecular attract each other.

Kinetic molecular model is used to explain the three states of matter - solid, liquid and gas.

SOLID 

A solid is an example of matter that holds its shape and thickness when not restricted. The modifier solid depicts the state, or condition, of matter having this property.

Solids such as a stone, metal spoon, pencil, etc. have fixed shapes and volume. Their molecules are held close together such as shown in fig bellow, by strong forces of attraction. However, they vibrate about their mean positions but do not move from place to place.

LIQUIDS

A liquid is an example of matter that complies with the state of a container in which it is held, and which gets a characterized surface within the sight of gravity. The term fluid is likewise utilized as a part of reference to the state, or condition, of matter having this property.

 The distance between the molecules of a liquid are more than in solids. Thus, attractive forces between them are weaker. Like solid, molecules of  a liquid also vibrate about their mean position but are not rigidly held with each other. Due to the weaker attractive forces, they can slide over one another. Thus the liquid can flow. The volume of certain amounts of liquids remain the same but because it can flow hence, it attains the shape of a container to which it is put.

GASES

A gas is an example of matter that complies with the state of a holder in which it is held and secures a uniform thickness inside the compartment, even within the sight of gravity and paying little heed to the measure of substance in the holder. If not limited to a holder, vaporous matter, otherwise called vapor, will scatter into space . The term gas is likewise utilized as a part of reference to the state, or condition, of matter having this property.

 Gases such as air have no fixed shape or volume. They can be filled in any container of any shape. Their molecules have random motion and move with very high velocities. In gases, molecules are much farther apart than solid or liquid such as shown in fig bellow. Thus gasses are much lighter than solid and liquids. Then can be squeezed into smaller volumes. The molecules of a gas are constantly striking the walls of container. Thus, a gas exerts pressure on the walls of the container. 

PLASMA - THE FOURTH STATE OF MATER

The kinetic energy of gas molecules goes on increasing if a gas is heated continuously. This causes the gas molecules to move faster and faster. The collision between atoms and molecules of the gas becomes so strong that they tear off the atoms. Atoms lose their electrons and become positive ions. This ionic state of matter is called plasma. Plasma is also formed in gas discharge tubes when electric current passes through these tubes.

 Plasma is also called Fourth State Of Matter. in which a gas occur in its ionic state. Positive ions and electrons get separated in the presences of electric or magnetic fields. Plasma also exist in neon and fluorescent tubes when they glow. Most of the matter that files the universe is in plasma state. In Stars such as our Sun, Gasses, exist in their ionic state. Plasma is highly conducting state of matter. It allows electric current to pass through it.

Differentiate Temperature and Heat

Temperature and Heat both are the type of energy. Here we discussed about difference between both.

Temperature

 When we touched a body we feel it hot or cold. The temperature of a body tells us how hot or cold a body is. Thus:

 "Temperature of a body is the degree of hotness or coldness of the body".

A candle flame is hot and is said to be at high temperature. Ice on the other hand is cold and is said to be at low temperature. Our sense is some what approximation and unreliable. Moreover, it is not always safe in touch a hot body. What we need is a reliable and practicable method to determine the relative hotness or coldness of bodies.

To understand the concept of temperature, it is useful to understand the terms, thermal contact and thermal equilibrium. To store ice in summer, people warp it to with cloth or keep it in wooden box or in thermos flask. In this way, they avoid thermal contact of ice with its hot surrounding other wise ice will soon melt away. Similarly, when you place a cup of hot tea or water in a room, it cool down gradually. Does it continue coiling? it stooped cooling as it reaches the room temperature. Thus temperature determines the direction of flow of heat. Heat flows from a hot body to a cold body until thermal equilibrium is reached.
What happens when we touched a hot body? Take two bodies having different temperatures. Bring them in contact with each other. The temperature of the hot body falls. This energy enters the cooled body at lower temperature. Cooled body gains energy and its temperature rises. The transfer of energy continuous till both the bodies have the same temperature.

Heat

 The form of energy that is transferred form a hot body to a cold body is called heat. Thus

"Heat is the energy that is transferred from one body to the other in thermal contact with each other as a result of the difference of temperature between them".

Heat is therefore, called as the energy in transit. Once heat enters a body, it becomes its internal energy and no longer exist as heat energy. 

           What is internal energy of a body?

"The sum of kinetic energy and potential energy associated with the atoms, molecules and particles of a body is called its internal energy".

Internal energy of a body depends on many factors such as the mass of a body, kinetic and potential energies of molecules etc. Kinetic energy of an atom or molecule is due to motion or which depends on the temperature. Potential energy of atoms or molecules is the stored energy due to inter molecular forces.

How Many Forms Of Energy?

Forms Of Energy

Forms Of Energy: Energy exist in various forms. Some of the main forms of energy are given in a bellow Fig.

Now we discussed her a few types of energy. These forms of energy are shown bellow.

• Mechanical Energy
• Heat Energy
• Electrical Energy
• Sound Energy
• Light Energy
• Chemical Energy
• Nuclear Energy

Mechanical Energy

  The energy possessed by a body due to its motion or position is called mechanical energy. Water running down a stream, wind, a moving car, a lifted hammer, a stretched bow, a catapult or a compressed spring etc. possess mechanical energy.

Heat Energy

  Heat is form of energy given out by hot bodies. Large amount of heat is obtained by burning fuel. Heat is also produced when motion is opposed by friction forces. The food we take provide us heat energy. The sun is the main source of heat energy.

Electrical Energy

  Electricity is one of the widely used form of energy. Electrical energy can be supplied easily to any desired place through wires. We get electrical energy from batteries and electric generators. These electrical generator are run by hydro power, thermal or nuclear power.

Sound Energy

  When you knock at the door, you produced sound. Sound is a form of energy. It's produced when a body vibrates such as vibrating diaphragm of a drum, vibrating strings of a sitar and vibrating air column of wind instruments such as flute pipe etc.

Light Energy

  Light is an important part of energy. Name some source of light that you come across.

Plants produce food in the presence of light. We also need light to see things. We get light from candles, electric bulbs, florescent tube, and also by burning fuels. However, most of the lights comes from the Sun.

Chemical Energy

  Chemical energy is present in food, fuels and in other substance. We get other forms of energy from these substances during chemical reactions. The burning woods, cool or natural gas in air is chemical reactions which release energy as heat and light. Electric energy is obtained from electric cells and batteries as a result of chemical reaction between various substances present in them. Animal gets heat and muscular energy from the food they eat.

Nuclear Energy

  Nuclear energy is the energy released in the form of nuclear radiation to heat and light during nuclear reactions such as Fission and Fusion reactions. Heat energy is released in nuclear reactors is converted into electrical energy.The energy coming from the sun for the last billions of year is the result of nuclear reactions taking place on the Sun.

What are 10 Major Different Sources of Energy?

Major Sources of Energy

Sources of Energy: The energy we use comes from the Sun, Wind, and water power etc. Actually, all of the energy we get comes directly or in directly from the Sun.

Fossil Fuels 

We use fossil fuels such as coal, oil and gas to heat our houses and run industry and transports. They are usually hydrocarbon (compounds of a carbon and hydrogen). When they are burnt, they combine with oxygen from the air. The carbon becomes carbon dioxide; hydrogen becomes hydrogen oxide called water; while energy is released as heat. In case of coal:

                           Carbon + Oxygen → Carbon dioxide + Heat Energy

                  Hydrogen + Oxygen  →  Carbon dioxide + Water + Heat energy

A gas field

The fuels took millions of years for their formation. They are known as non-renewable resources. We are using fossil fuels at a very fast rate. Their use is increasing day by day to meet our energy needs. If we continue to use them at present rate, they will soon be exhausted. Once their supply is exhausted, the world would face serious energy crisis.

Thus fossil fuels would not be able to meet our future energy needs.This would causes serious social and economical problem for countries like us. Therefore, we must use wisely and at the same time develop new energy sources for our future survival. 

Nuclear Fuels

In nuclear power plants, we get energy as  a result of fission reaction. Nuclear power plants gives out a lot of nuclear radiation and vast amount of heat. A part of this heat is used to run power plants while lot of heat goes waste into the environment.

Renewable Energy Sources 

Sunlight and water power are the renewable source of energy. They will not run out like coal, oil and gas.

Energy From Water

Energy from water power is very cheap. Dams are being contributed at suit able locations in different parts of the world. Dams serve many purposes. They help to control flood by storing water. The water stored in the dams is used for irrigation and also to generate electrical energy without creating much environmental problems.

Energy From The Sun

 Solar energy is the energy coming from the sun and is used directly or indirectly. Sunlight does not pollute the environment in any way. The sun rays are the ultimate source of life on the earth. We are depend on the sun for all over food and fuels. If we find a suitable method to use fraction of the solar energy reaching  the earth then it would be enough to fulfill our energy requirement.

Solar House Heating

 The use of solar energy is not new. However, it is used in houses and offices as well as for commercial industrial purposes is quit recent. Complete solar house heating system are success fully used in areas with the minimum amounts of sunshine in the winter. A heating system consist of:

• A collector 
• A storage devices 
• A distribution system

Solar collector is made of glass panels over blank metal plates. The plates absorb the Sun's energy which heats a liquid flowing in the pipes at the back of the collector. The hot water can be used for cooking, washing and heating the buildings. Solar energy is used in a solar cookers, solar distribution plants, solar power plants etc.

Solar Cells

Solar energy can also be converted directly into electricity by Solar cells. A solar cell also called photo cell is made from silicon water. When sun light falls on a solar cells, it converts the light directly into electrical energy. Solar cells also be used in calculator, watches and toys.

   Several other methods to trap sun rays are under way. If scientist could find an efficient and inexpensive method to use solar energy, then the people would get clean, limitless energy as long as the sun continues to shine.

Wind Energy

Wind has been used a a source of energy from the centuries. It has power sailing ships across the oceans. It has been used by windmills to grind grain and pump water. Moreover, wind power is used to turn winds turbines. In the United States, some wind farms generate more than 1300 MW of electricity per day. In Europe, many wind farms routinely generate hundred megawatts or more than electricity a day.

Geo Thermal Energy

     In some part of the world, the earth provides us hot water from geyser and hot springs. There is hot molten part, deep in the earth is called magma. Water reaching close to the magma. Water reaching close to the magma changes to steam due to the high temperature of magma. This type of energy is called Geo Thermal energy.

Energy From Biomass 

Biomass is plant or animal wastes that can be burn as fuel. Other forms of biomass is garbage, farm wastes, sugarcane and other plants. These wastes are used to run power plants.Many industries that used forest products get half of their by burning bark and other woods wastes. Biomass can serve as another energy source, but the problems are there in its use.

  When animal dung, dead plants and dead animals decompose, they give off a mixture of methane and carbon dioxide. Electricity can be generated by burning methane

WHAT IS RIPPLE TANK?

Ripple Tank

Ripple tank is a device to produced water waves and to study their characteristics.

This apparatus consist of a rectangular tray glass bottom and is placed nearly half meter above the surface of a table. Waves can be produced on the surface of the water present in the tray by means of vibrator (paddle).

ripple tank apparatus

This Vibrator is an oscillating electric motors fixed on a wooden plate over the tray such that its lower surface just touches the surface of water. On setting the vibrator ON,  this wooden plate stats vibrating to generate water waves consist of straight wave fronts. An electric bulb is hung above the tray of observer the image of water wave on the paper or screen. The crests and the through of the waves appear as bright and dark lines respectively, on the screen.

Now we explain the reflection of water waves with the helps of ripple tank. Placed the barrier in the ripple tank. The water wave will be reflect from the barrier. If the barrier is placed at an angle to the wave front, the reflected wave can be seen to obey the law of reflection i.e,the angle of the incident wave along the normal will be equal to the angle of the reflected wave. Therefore we characterize Reflection of Wave as:

When waves moving in one medium fall on the surface of another medium they skip again into the main medium with the end goal that the point of the occurrence is equivalent to the edge of reflection.

The speed of a wave in water depends on the depth of water. On the off chance that the square is submerged in the ripple tank, the profundity of water in the tank will be shall allow water their wavelength will diminishes. But the frequency of the water wave remain the same in both parts of water because it is equal to the frequency of the vibrator. 

For the perception of refraction of water waves, we rehash the above examination with the end goal that the limit between the profound and the shallower water is at some point to the wave front. Now we will observe that in addition to the change in wavelength, the waves change their direction of propagation as well. Note that the direction of propagation is always normal to the wave fronts. This change of path off water waves will passing through the region of deep water to that of shallower one is called Refraction which is define as:

When a wave from one medium enters into the second medium at some angle, its direction of travel changes.

Now we observe the phenomenon of diffraction of water waves. Generate Straight waves in a ripple tank and place two obstacles in line in such a way that separation between them is equal to the wavelength of water waves. In the wake of going through a little opening between the two deterrents, the waves will spread toward each path and change into practically half circle design.

Differentiation of water waves

Differentiation of waves can only be observed clearly if the size of the obstacles is comparable with the with the wavelength of the wave. Differentiation of waves while passing through a slit with size larger than the wavelength of the wave. Only a small differentiation is occurs near the corner of the obstacle.

The bending or spreading of the waves around the sharp edges or corner of obstacles or slits is called diffraction.

INTERNET | INTERNET SERVICES | BROWSERS | ELECTRONIC MAIL

What is Internet?

 When many computer networks of the world were connected together. with the object of communicating with each other, Internet was formed. In other words, we can say that internet is a network of networks, which speed all across the globe. Initially, the size of internet was small. Soon people became aware of this utility. and advantages and with in short span of time, numerous computers and network got themselves connected to internet. It size has increased multi fold with in Years. Today internet comprises of several million computers. There is hardly any country of the world and important city of the country. 

A conceptual diagram of internet is illustrate in a bellow fig.  Internet is basically a large computer network, which extends all across the globe. In internet, millions of computers remain connected to each other through well-laid communication system.

schematic diagram of internet

Recall that telephone communication system is well defined, time proven system.Internet make use of this system and many other system to connect all the computers. Thus like a Telephone connection, any computer of any city can established a connection with any other computer of any city and exchange data or message with it.

Internet Services

 INTERNET SERVICES: The main services used on the internet include: 

• Web browsing - this function allows user to view web pages.
• Web - Allows people to send and receive text message.

Browsers 

 A browser is an application which provides a window to the web. All browsers a design to display the pages of information located at the websites around the world. The most popular browser in the market today include Internet Explorer, The World, Opera, Mozilla Firefox, Chrome, etc.

We can search anything through search engine like Google Chrome, Internet Explorer, Mozilla Firefox, etc.

Electric Mail

One of the most widely used application of internet is Electric Mail (or E- mail), which provides very fast delivery of message to any enable site on the internet. Communication through e-mail is more quick and reliable. Through our w-mail, we can communicate with our friends and institution with more ease and pace. Some advantages of e-mail are also follows:

Fast Communication

 We can sent Message anywhere in the world instantly.

Cost Free Services 

If we have internet access, then we can avail the e-mail services free for cost.

Simple To Use

After initial setup of e-mail account, it is easy to use.

More Efficient 

 We can send our message to many friends or many people just in one second.

Versatile

Pitcher or many other files can also be send through e-mail.

Internet is proved to be very beneficial to us. Here is the list of us of internet.

1. Faster communication
2. Big source of information
3. Source of entertainment
4. Access of social media
5. Access to online Services
6. E-commerce
7. E-learning