Technical Description

TECHNICAL DESCRIPTION

1. ACair conditioner (often referred to as AC) is a home appliance, system, or mechanism designed to dehumidify and extract heat from an area. The cooling is done using a simple refrigeration cycle. In construction, a complete system of heating, ventilation and air conditioning is referred to as "HVAC".

In the refrigeration cycle, a heat pump transfers heat from a lower-temperature heat source into a higher-temperature heat sink. Heat would naturally flow in the opposite direction. This is the most common type of air conditioning. A refrigerator works in much the same way, as it pumps the heat out of the interior and into the room in which it stands.

A simple stylized diagram of the refrigeration cycle: 1) condensing coil, 2) expansion valve, 3) evaporator coil, 4) compressor.

This cycle takes advantage of the way phase changes work, where latent heat is released at a constant temperature during a liquid/gas phase change, and where varying the pressure of a pure substance also varies its condensation/boiling point.Freon is a good refrigerant.

running a normal air conditioner's refrigerant in the opposite direction, the overall effect is the opposite, and the compartment is heated. This is usually called a heat pump, and is capable of heating a home to comfortable temperatures (25 °C; 70 °F), even when the outside air is below the freezing point of water (0 °C; 32 °F)@@@@

Humidity

Air conditioning equipment usually reduces the humidity of the air processed by the system. The

relatively cold (below the dew point) evaporator coil condenses water vapor from the processed

air, much as a cold drink will condense water on the outside of a glass. The water is drained,

removing water vapor from the cooled space and thereby lowering its relative humidity.

Basic parts

The following are the basic parts for a window unit air conditioner.

[edit]Exterior

Adjustable louvers

Control panel

Front grill

Thermostat sensor

[edit]Interior

Blower

Partition

Fan

Compressor

Condenser coil

Evaporator coil

Filter

@2. TELEPHONEThe telephone (from the Greek: τῆλε, tēle, "far" and φωνή, phōnē, "voice"),

often colloquially referred to as a phone, is atelecommunications device that transmits and

receives sound, most commonly the human voice. Telephones are a point-to-pointcommunication

system whose most basic function is to allow two people separated by large distances to talk to

each other. It is one of the most common appliances in the developed world, and has long been

considered indispensable to businesses, households and governments. The word "telephone"

has been adapted to many languages and is widely recognized around the world.

All telephones have a microphone to speak into, an earphone which reproduces the voice of the

other person, a ringer which makes a sound to alert the owner when a call is coming in, and

a keypad (or in older phones a telephone dial or no manual device) to enter the telephone

number of the telephone being called. The microphone and earphone are usually built into

ahandset which is held up to the face to talk. The keypad may be part of the handset or of a base

unit to which the handset would be connected. A landline telephone is connected by a pair of

wires to the telephone network, while a mobile phone or cell phoneis portable and communicates

with the telephone network by radio. A cordless telephone has a portable handset which

communicates by radio with a base station connected by wire to the telephone network, and can

only be used within a limited range of the base station. Along with the microphone and speaker,

additional circuitry is incorporated to prevent the incoming speaker signal and the outgoing

microphone signal from interfering with each other. This is accomplished through a hybrid

coil (A3)

The microphone converts the sound waves to electrical signals, which are sent through

the telephone network to the other phone, where they are converted back to sound waves by

the earphone in the other phone's handset. Telephones are a duplexcommunications medium,

meaning they allow the people on both ends to talk simultaneously. The telephone network,

consisting of a worldwide net of telephone lines, fiberoptic cables,microwave

transmission, cellular networks, communications satellites, and undersea telephone

cables connected by switching centers, allows any telephone in the world to communicate with

any other. Each telephone line has an identifying number called its telephone number. To initiate

a telephone call, a conversation with another telephone, the user enters the other telephone's

number into a numeric keypad on his/her phone.

3.Solar cookerA solar cooker, or solar oven, is a device which uses the energy of sunlight to heat food or drink to cook it or sterilize it. High-tech versions, for example electric ovens powered bysolar cells, are possible, and have some advantages such as being able to work in diffuse light. However at present they are very unusual because they are expensive. The vast majority of the solar cookers presently in use are relatively cheap, low-tech devices. Because they use no fuel and cost nothing to operate, many nonprofit organizations are promoting their use worldwide to help reduce fuel costs for low-income people, reduce air pollution and slow deforestation and desertification, caused by use of firewood for cooking. Solar cooking is a form ofoutdoor cooking and is often used in situations where minimal fuel consumption is important, or the danger of accidental fires is high.

There are a variety of types of solar cookers: over 65 major designs and hundreds of variations of

them. The basic principles of solar cooker design are:

Concentrating sunlight: A reflective mirror of polished glass, metal or metallised film is

used to concentrate light and heat from the sun into a small cooking area, making the energy

more concentrated and increasing its heating power.

Converting light to heat: A black or low reflectivity surface on a food container or the

inside of a solar cooker will improve the effectiveness of turning light into heat.

Light absorptionconverts the sun's visible light into heat, substantially improving the

effectiveness of the cooker.

Trapping heat: It is important to reduce convection by isolating the air inside the cooker

from the air outside the cooker. A plastic bag or tightly sealed glass cover will trap the hot air

inside. This makes it possible to reach similar temperatures on cold and windy days as on

hot days.

Greenhouse effect : Glass transmits visible light but blocks infrared thermal radiation from

escaping. This amplifies the heat trapping effect.

Box cookers

A box cooker has a transparent glass or plastic top, and it may have additional reflectors to

concentrate sunlight into the box. The top can usually be removed to allow dark pots containing

food to be placed inside. One or more reflectors of shiny metal or foil-lined material may be

positioned to bounce extra light into the interior of the oven chamber. Cooking containers and the

inside bottom of the cooker should be dark-colored or black.

Give advantages!!!

4. SOLAR WATER HEATER

Hot water heated by the sun is used in many ways. While perhaps best known in a residential

setting to provide domestic hot water, solar hot water also has industrial applications, e.g. to

generate electricity.[1] Designs suitable for hot climates can be much simpler and cheaper, and

can be considered an appropriate technology for these places. The global solar thermal market is

dominated by China, Europe, Japan and India.

A solar hot water heater installed on a house in Belgium

In order to heat water using solar energy, a collector, often fastened to a roof or a wall facing the

sun, heats working fluid that is either pumped (active system) or driven by natural

convection (passive system) through it. The collector could be made of a simple glass topped

insulated box with a flat solar absorber made of sheet metal attached to copper pipes and painted

black, or a set of metal tubes surrounded by an evacuated (near vacuum) glass cylinder. In

industrial cases a parabolic mirror can concentrate sunlight on the tube. Heat is stored in a hot

water storage tank. The volume of this tank needs to be larger with solar heating systems in order

to allow for bad weather, and because the optimum final temperature for the solar collector is

lower than a typical immersion or combustion heater. The heat transfer fluid (HTF) for the

absorber may be the hot water from the tank, but more commonly (at least in active systems) is a

separate loop of fluid containing anti-freeze and a corrosion inhibitor which delivers heat to the

tank through a heat exchanger (commonly a coil of copper tubing within the tank)..

Residential solar thermal installations fall into two groups: passive (sometimes called "compact")

and active (sometimes called "pumped") systems. Both typically include an auxiliary energy

source (electric heating element or connection to a gas or fuel oil central heating system) that is

activated when the water in the tank falls below a minimum temperature setting such as 55°C.

Hence, hot water is always available. The combination of solar water heating and using the back-

up heat from a wood stove chimney to heat water[2] can enable a hot water system to work all

year round in cooler climates, without the supplemental heat requirement of a solar water heating

system being met with fossil fuels or electricity.

When a solar water heating and hot-water central heating system are used in conjunction, solar

heat will either be concentrated in a pre-heating tank that feeds into the tank heated by

the central heating, or the solar heat exchanger will replace the lower heating element and the

upper element will remain in place to provide for any heating that solar cannot provide. However,

the primary need for central heating is at night and in winter when solar gain is lower. Therefore,

solar water heating for washing and bathing is often a better application than central heating

because supply and demand are better matched. In many climates, a solar hot water system can

provide up to 85% of domestic hot water energy. This can include domestic non-

electric concentrating solar thermal systems. In many northern European countries, combined hot

water and space heating systems (solar combisystems) are used to provide 15 to 25% of home

heating energy.

The type, complexity, and size of a solar water heating system is mostly determined by:

The temperature and amount of the water required from the system.

Changes in ambient temperature and solar radiation between summer and winter.

The changes in ambient temperature during the day-night cycle.

The possibility of the potable water or collector fluid overheating.

The possibility of the potable water or collector fluid freezing.

5)ELECTRIC GEYSER

Geysers work on the principle of conversion of electrical energy into heat energy by using a heating element. Cold water comes into a defined compartment, gets heated to a certain degree, by the heating element and goes out through another outlet. ISI marked geysers are preferred over local makes because they have incorporated essential safety norms.

The standard geyser is 15lt in capacity, although 1lt capacity geysers are also available. These electrical appliances have insulated body with long life heating element. There are multiple safety systems installed in geysers to avoid any kind of mishap. These geysers come with a minimum guarantee period but have quite a good life. Combistat is also fitted for maintaining temperature and to conserve energy.

Electrical Geysers are classified as per their capacity, where the starting range is one liter and extends up to 25liters, depending on the requirement of any household. 

Instant Geysers are geysers which take very little time to heat water and have lesser capacity as compared to traditional geysers. Fusible plug, pressure release valve, thermal cut out and ISI approved thermostat are some of the features of instant geysers. They are good for small families because standard geysers consume more electricity to heat large quantity of water. Instant geysers are also successful in kitchens where water consumption is only for cleaning of utensils.

Geysers are also classified according to energy consumption. Some large capacity geysers consume lesser electricity, despite their higher capacity. These geysers are given ratings of 4stars and 3stars respectively. The higher number of stars denotes higher efficiency and therefore low energy consumption. Those electrical kitchen accessories should be purchased which have good ratings to save on energy and enjoy greater efficiency.

Electrical Geysers are available in different shades to go with the interiors of your bathroom and kitchen. 

The function of the thermostat is to set the temperature to a certain value so that water is not heated above that value.

The tank is normally covered with some insulating material such as glass wool and entire assembly is enclosed inside a metal casing which can be hanged on the wall or wherever required.

6. MICROWAVESA microwave oven (often referred to colloquially simply as a "microwave") is a kitchen appliance that heats food by dielectric heating. This is accomplished by using microwave radiation to heat polarized molecules within the food. This excitation is fairly uniform in the outer 1 inch (25 mm) to 1.5 inches (38 mm) inches of a dense (high water content) food item, leading to food being more evenly heated throughout (except in thick dense objects) than generally occurs in other cooking techniques.

Basic microwave ovens heat foods quickly and efficiently, but, unlike conventional ovens, do not brown or bake food. This makes them unsuitable for cooking certain foods, or to achieve certain culinary effects. Additional kinds of heat sources can be added to microwavepackaging, or into combination microwave ovens, to produce these other heating effects.

A microwave oven works by passing non-ionizing microwave radiation, usually at a frequency of 2.45 gigahertz (GHz)—a wavelength of 122 millimetres (4.80 in)—through the food. Microwave radiation is between common radio and infrared frequencies. Water, fat, and other substances in the food absorb energy from the microwaves in a process called dielectric heatingRotating molecules hit other molecules and put them into motion, thus dispersing energy. This energy, when dispersed as molecular vibration in solids and liquids (i.e., as both potential energy andkinetic energy of atoms), is heat.

A microwave oven consists of:

a high voltage power source, commonly a simple transformer or an electronic power

converter, which passes energy to the magnetron

a high voltage capacitor connected to the magnetron, transformer and via a diode to the

case.

a cavity magnetron, which converts high-voltage electric energy to microwave radiation

a magnetron control circuit (usually with a microcontroller)

a waveguide (to control the direction of the microwaves)

a cooking chamber

7 MOBILE PHONE

A mobile phone allows calls into the public switched telephone system over a radio link. Early

mobile phones were usually bulky and permanently installed in vehicles; they provided limited

service because only a few frequencies were available for a geographic area. Moderncellular

"cell" phones or hand phones make use of the cellular network concept, where frequencies are

re-used repeatedly within a city area, allowing many more users to share access to the radio

bandwidth. A mobile phone allows calls to be placed over a wide geographic area; generally the

user is a subscriber to the phone service and does not own the base station. By contrast,

a cordless telephone is used only within the range of a single, private base station.

A mobile phone can make and receive telephone calls to and from the public telephone

network which includes other mobiles and fixed-linephones across the world. It does this by

connecting to a cellular network provided by a mobile network operator.

In addition to telephony, modern mobile phones also support a wide variety of other services such

as text messaging, MMS, email, Internet access, short-range wireless communications

(infrared, Bluetooth), business applications, gaming and photography. Mobile phones that offer

these more general computing capabilities are referred to as smartphones.

ELLABORATE ON APPLICATIONS

8)RECTIFIERA rectifier is an electrical device that converts alternating current (AC), which periodically

reverses direction, to direct current (DC) which flows in only one direction. The process is known

as rectification. Physically, rectifiers take a number of forms, including vacuum

tube diodes, mercury arc valves, solid state diodes, silicon-controlled rectifiers and other silicon-

based semiconductor switches. Historically, even synchronous electromechanical switches and

motors have been used. Early radio receivers, called crystal radios, used a "cat's whisker" of fine

wire pressing on a crystal of galena (lead sulfide) to serve as a point-contact rectifier or "crystal

detector".

Rectifiers have many uses, but are often found serving as components of DC power

supplies and high-voltage direct current power transmission systems. Rectification may serve in

roles other than to generate direct current for use as a source of power. As

noted, detectors of radio signals serve as rectifiers. In gas heating systems flame rectification is

used to detect presence of flame.

The simple process of rectification produces a type of DC characterized by pulsating voltages and

currents (although still unidirectional). Depending upon the type of end-use, this type of DC

current may then be further modified into the type of relatively constant voltage DC

characteristically produced by such sources as batteries and solar cells.

A device which performs the opposite function (converting DC to AC) is known as an inverter.

In half wave rectification, either the positive or negative half of the AC wave is passed, while the

other half is blocked. Because only one half of the input waveform reaches the output, it is very

inefficient if used for power transfer. Half-wave rectification can be achieved with a single diode in

a one-phase supply, or with three diodes in a three-phase supply.

Full-wave rectification

A full-wave rectifier converts the whole of the input waveform to one of constant polarity (positive

or negative) at its output. Full-wave rectification converts both polarities of the input waveform to

DC (direct current), and is more efficient. However, in a circuit with a non-center

tapped transformer, four diodes are required instead of the one needed for half-wave rectification.

(See semiconductors, diode). Four diodes arranged this way are called a diode bridge or bridge

rectifier.

9. EATHRQUAKE

An earthquake (also known as a quake, tremor or temblor) is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time. Earthquakes are measured using observations from seismometers. The moment magnitude is the most common scale on which earthquakes larger than approximately 5 are reported for the entire globe. 

At the Earth's surface, earthquakes manifest themselves by shaking and sometimes

displacement of the ground. When theepicenter of a large earthquake is located offshore, the

seabed may be displaced sufficiently to cause a tsunami. Earthquakes can also trigger

landslides, and occasionally volcanic activity.

In its most general sense, the word earthquake is used to describe any seismic event — whether

natural or caused by humans — that generates seismic waves. Earthquakes are caused mostly

by rupture of geological faults, but also by other events such as volcanic activity, landslides, mine

blasts, and nuclear tests. An earthquake's point of initial rupture is called its focus orhypocenter.

The epicenter is the point at ground level directly above the hypocenter. 7 MAJOR PLATES,

KEEP COLLIDING.

10 NATURAL GEYSERA geyser (US / ̍ ɡ a ɪ z ər / ; UK / ̍ ɡ i ː z ə / [1] ) is a spring characterized by intermittent discharge of water

ejected turbulently and accompanied by a vapour phase (steam). The word geyser comes

from Geysir, the name of an erupting spring at Haukadalur, Iceland; that name, in turn, comes

from the Icelandic verb geysa, "to gush", the verb itself from Old Norse.

The formation of geysers is due to particular hydrogeological conditions, which exist in only a few

places on Earth, so they are a fairly rare phenomenon. Generally all geyser field sites are located

near active volcanic areas, and the geyser effect is due to the proximity ofmagma. Generally,

surface water works its way down to an average depth of around 2,000 metres (6,600 ft) where it

contacts hot rocks. The resultant boiling of the pressurized water results in the geyser effect of

hot water and steam spraying out of the geyser's surface vent (a hydrothermal explosion).

About a thousand known geysers exist worldwide, roughly half of which are in Yellowstone

National Park, Wyoming, United States. A geyser's eruptive activity may change or cease due to

ongoing mineral deposition within the geyser plumbing, exchange of functions with nearby hot

springs, earthquake influences, and human intervention.[2]

Geysers are temporary geological features. Geysers are generally associated with volcanic

areas.[3] As the water boils, the resulting pressure forces a superheated column of steam and

water to the surface through the geyser's internal plumbing. The formation of geysers specifically

requires the combination of three geologic conditions that are usually found in volcanic terrain.[3]

Intense heat

The heat needed for geyser formation comes from magma that needs to be near the

surface of the earth. The fact that geysers need heat much higher than normally found

near the earth's surface is the reason they are associated with volcanoes or volcanic

areas. The pressures encountered at the areas where the water is heated makes the

boiling point of the water much higher than at normal atmospheric pressures.

Water

The water that is ejected from a geyser must travel underground through deep,

pressurized fissures in the earth's crust.

A plumbing system

In order for the heated water to form a geyser, a plumbing system is required. This

includes a reservoir to hold the water while it is being heated. Geysers are generally

aligned along faults.[3] The plumbing system is made up of a system of fractures, fissures,

porous spaces and sometimes cavities. Constrictions in the system are essential to the

building up of pressure before an eruptio

11)IRONAn iron is a small appliance used in ironing to remove wrinkles from fabric. Ironing works by loosening the ties between the long chains of molecules that exist in polymer fiber materials. With the heat and the weight of the ironing plate, the fibers are stretched and the fabric

maintains its new shape when cool. Some materials such as cotton require the use of water to loosen the intermolecular bonds. Many materials developed in the twentieth century are advertised as needing little or no ironing.

Modern irons for home use can have the following features:

a method for setting the iron down, usually standing on its end, without the hot soleplate

touching anything that could be damaged;

a thermostat ensuring maintenance of a constant temperature;

a temperature control dial allowing the user to select the operating temperatures (usually

marked with types of cloth rather than temperatures:silk, "wool", "cotton", "linen", etc.);

electrical cord with heat-resistant Teflon (PTFE) insulation;

ejection of steam through the clothing during the ironing process;

A water reservoir inside the iron used for steam generation;

An indicator showing the amount of water left in the reservoir,

Constant steam - constantly sends steam through the hot part of the iron into the

clothes;

Steam burst - sends a burst of steam through the clothes when the user presses

a button;

12) ELECTRIC FANA mechanical fan is a machine used to create flow within a fluid, typically a gas such as air.

A fan consists of a rotating arrangement of vanes or blades which act on the air. Usually, it is

contained within some form of housing or case. This may direct the airflow or increase safety by

preventing objects from contacting the fan blades. Most fans are powered by electric motors, but

other sources of power may be used, including hydraulic motors and internal combustion

engines and solar power.

Fans produce air flows with high volume and low pressure, as opposed to compressors which

produce high pressures at a comparatively low volume. A fan blade will often rotate when

exposed to an air stream, and devices that take advantage of this, such

as anemometers and wind turbines, often have designs similar to that of a fan.

For more details on this topic, see Centrifugal compressor.

While fans are often used to cool people, they do not actually cool air (if anything, electric fans

warm it slightly due to the warming of their motors), but work by evaporative cooling of sweat and

increased heat conduction into the surrounding air due to the airflow from the fans. Thus, fans

may become at ineffective at cooling the body if the surrounding air is near body temperature and

contains high humidity.

The axial-flow fans have blades that force air to move parallel to the shaft about which the blades rotate. Axial fans blow air along the axis of the fan, linearly, hence their name. This type of fan is used in a wide variety of applications, ranging from small cooling fans for electronics to the giant fans used in wind tunnels. Axial flow fans are applied for air conditioning and industrial process applications. Standard axial flow fans have diameters from 300-400 mm or 1800 to 2000 mm and work under pressures up to 800 Pa.

13 CYCLONE a cyclone is an area of closed, circular fluid motion rotating in the same direction as the Earth.[1][2] This is usually characterized by inward spiraling winds that rotate anticlockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere of the Earth. Most large-scale cyclonic circulations are centered on areas of low atmospheric pressure.

FORMATIONCyclones (including typhoons and hurricanes) are caused by warm tropical moisture bearing clouds developing in open oceans or seas. Cyclones can only form over warm waters in the tropical regions of the oceans where the sea temperatures are 26.5 degrees Celsius or higher (around 80 degrees Fahrenheit). They occur in areas of very low pressure when air that is heated by the sun rises rapidly, and becomes saturated with moisture which then condenses into high thunderclouds. As the atmosphere becomes favorable for development (no wind shearing in the higher parts of the atmosphere), normal thunder storms clump together. 

When the hot air rises, cooler air rushes in to fill the area left vacant by the hot air. The Coriolis effect of the Earth spinning on its axis causes the air to spiral upwards with considerable force. This in turn causes the winds to rotate faster, causing the tropical low to deepen in intensity into a tropical depression, and eventually a cyclone which is anywhere between hundreds of kilometres to thousands of kilometres wide. 

Cyclones are also characterised by strong winds, yet in their centre is a clear, calm region called the 'eye'. When the cyclone continues its course, and the winds return from the other direction, they may seem to be more violent. The winds are not just rotating; there is also the effect of the warmer air continually rising and cold air rushing in. That is why the winds are so strong, and seem to move in all directions. 

Winds gusts in a category 5 cyclone can exceed 280 kph, and a fully developed cyclone pumps out about two million tonnes of air per second.

Structure

There are a number of structural characteristics common to all cyclones.The cyclones have high

pressure outside and low pressure inside. A cyclone is a low pressure area.[13] A cyclone's center

(often known in a mature tropical cyclone as the eye), is the area of lowest atmospheric pressure

in the region.[13] Near the center, the pressure gradient force (from the pressure in the center of

the cyclone compared to the pressure outside the cyclone) and the force from the Coriolis

effect must be in an approximate balance, or the cyclone would collapse on itself as a result of

the difference in pressure.[14]

Because of the Coriolis effect, the wind flow around a large cyclone is counterclockwise in the

Northern Hemisphere and clockwise in the Southern Hemisphere.[15] In the Northern Hemisphere,

the fastest winds relative to the surface of the Earth therefore occur on the eastern side of a

northward-moving cyclone and on the northern side of a westward-moving one; the opposite

occurs in the Southern Hemisphere.[16] (The wind flow around an anticyclone, on the other hand,

is clockwise in the northern hemisphere, and counterclockwise in the southern hemisphere.

EFFECTS:

loss of life and property. Many become homeless. Even the biggest countries are not spared.

MAKE A FLOW CHART!!!!!!

14 VOLCANOES1.  volcano is an opening, or rupture, in a planet's surface or crust, which allows

hot magma, volcanic ash and gases to escape from below the surface.

Volcanoes are generally found where tectonic plates are diverging or converging. A mid-oceanic

ridge, for example the Mid-Atlantic Ridge, has examples of volcanoes caused by divergent

tectonic plates pulling apart; the Pacific Ring of Fire has examples of volcanoes caused

by convergent tectonic plates coming together. By contrast, volcanoes are usually not created

where two tectonic plates slide past one another. Volcanoes can also form where there is

stretching and thinning of the Earth's crust in the interiors of plates.

Divergent plate boundaries

Main article: Divergent boundary

At the mid-oceanic ridges, two tectonic plates diverge from one another. New oceanic crust is

being formed by hot molten rock slowly cooling and solidifying. The crust is very thin at mid-

oceanic ridges due to the pull of the tectonic plates. The release of pressure due to the thinning of

the crust leads to adiabatic expansion, and the partial melting of the mantle causing volcanism

and creating new oceanic crust. Most divergent plate boundaries are at the bottom of the oceans,

therefore most volcanic activity is submarine, forming new seafloor. Black smokers or deep sea

vents are an example of this kind of volcanic activity. Where the mid-oceanic ridge is above sea-

level, volcanic islands are formed, for example, Iceland.

Convergent plate boundaries

Main article: Convergent boundary

Subduction zones are places where two plates, usually an oceanic plate and a continental plate,

collide. In this case, the oceanic plate subducts, or submerges under the continental plate forming

a deep ocean trench just offshore. Water released from the subducting plate lowers the melting

temperature of the overlying mantle wedge, creating magma. This magma tends to be

very viscous due to its high silicacontent, so often does not reach the surface and cools at depth.

When it does reach the surface, a volcano is formed. Typical examples for this kind of volcano

are Mount Etna and the volcanoes in the Pacific Ring of Fire.

"Hotspots"

Main article: Hotspot (geology)

"Hotspots" is the name given to volcanic provinces postulated to be formed by mantle plumes.

These are postulated to comprise columns of hot material that rise from the core-mantle

boundary. They are suggested to be hot, causing large-volume melting, and to be fixed in space.

Because the tectonic plates move across them, each volcano becomes dormant after a while and

a new volcano is then formed as the plate shifts over the postulated plume. The Hawaiian

Islands.

Cross-section through a stratovolcano (vertical scale is exaggerated):

1. Large magma chamber2. Bedrock3. Conduit (pipe)4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank

9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15. Ash cloud

15 FRIDGE

A refrigerator (commonly referred to as a fridge) is a common household appliance that consists

of a thermally insulated compartment and aheat pump (mechanical, electronic, or chemical)

which transfers heat from the inside of the fridge to its external environment so that the inside of

the fridge is cooled to a temperature below the ambient temperature of the room. Cooling is a

popular food storage technique in developed countries and works by decreasing the reproduction

rate of bacteria. The device is thus used to reduce the rate of spoilage of foodstuffs.

A refrigerator maintains a temperature a few degrees above the freezing point of water. Optimum

temperature range for perishable food storage is 3 to 5 °C (37 to 41 °F).[1] A similar device which

maintains a temperature below the freezing point of water is called a freezer.

The refrigerator is a relatively modern invention among kitchen appliances.

Vapor Compression Cycle – A: hot compartment (kitchen), B: cold compartment (refrigerator box), I: insulation, 1:

Condenser, 2: Expansion valve, 3: Evaporator unit, 4: Compressor

Features

Newer refrigerators may include:

Automatic defrosting ;

A power failure warning, alerting the user by flashing a temperature display. The

maximum temperature reached during the power failure may be displayed, along with

information on whether the frozen food has defrosted or may contain harmful bacteria;

Chilled water and ice available from an in-door station, so that the door need not be

opened;

Water and Ice Dispensing became available in the 1970s. Also some refrigerators have

icemakers built-in so the user doesn't have to use ice trays. Some refrigerators have water

chillers and water filtration systems.

Cabinet rollers that allow the refrigerator to be easily rolled around for easier cleaning;

Adjustable shelves and trays which can be repositioned to suit the user;

A Status Indicator to notify the user when it is time to change the water filter;

An in-door ice caddy, which relocates the ice-maker storage to the freezer door and

saves approximately 60 litres (2 cu ft) of usable freezer space. It is also removable, and helps

to prevent ice-maker clogging;

A cooling zone in the refrigerator door shelves. Air from the freezer section is diverted to

the refrigerator door, to cool milk or juice stored in the door shelf.

workingA vapor compression cycle is used in most household refrigerators, refrigerator–freezers and freezers. In this cycle, a circulating refrigerant such as R134a enters a compressor as low-pressure vapor at or slightly above the temperature of the refrigerator interior. The vapor is compressed and exits the compressor as high-pressure superheated vapor.

16 TVTelevision (TV) is a telecommunication medium for transmitting and receiving moving images that can be monochrome (black-and-white) or colored, with accompanying sound

the most common usage of the medium is for broadcast television, which was modeled on the existing radio broadcasting systems developed in the 1920s, and uses high-powered radio-frequency transmitters tobroadcast the television signal to individual TV receivers.

A standard television set comprises multiple internal electronic circuits, including those for receiving and decoding broadcast signals. A visual display device which lacks a tuner is properly called a video monitor, rather than a television. A television system may use different technical standards such as digital television (DTV) and high-definition television (HDTV). Television systems are also used for surveillance, industrial process control, and guiding of weapons, in places where direct observation is difficult or dangerous.

An analog television works by transferring electromagnetic waves into sound and light energy. The TV box works much like any receiver, in that it takes in electrical impulses sent from elsewhere and changes those bits of information into something people can hear and see. You can see a picture on a television because the cathode ray tube, in side older televisions, emits or fluoresces light not visible to the naked eye. The term "watch the tube," refers to the cathode ray tube present in most modern-day television sets.

Color on a television set is created by mixing various light beams. It basically works by regulating red, blue and green light in different patterns against something called a "phosphor sheet." TVs all have sheets placed behind the glass portion of it. Black and white televisions usually only have one phosphor sheet while color TVs will have three. By manipulating the "color burst," or composite video impulse, you can literally open up a suppressed TV signal for viewing.

MAKE FLOW CHART

17 VACUUM CLEANERSA vacuum cleaner, commonly referred to as a "vacuum," is a device that uses an air pump to create a partial vacuum to suck up dust and dirt, usually from floors, and optionally from other surfaces as well. The dirt is collected by either a dustbag or a cyclone for later disposal. Vacuum cleaners, which are used in homes as well as in industry, exist in a variety of sizes and models: small battery-operated hand-held devices, domestic central vacuum cleaners, huge stationary industrial appliances that can handle several hundred litres of dust before being emptied, and self-propelled vacuum trucks for recovery of large spills or removal of contaminated soil.

Technology

A vacuum's suction is caused by a difference in air pressure. An electric fan reduces the pressure

inside the machine. Atmospheric pressure then pushes the air through the carpet and into the

nozzle, and so the dust is literally pushed into the bag.

Tests have shown that vacuuming can kill 100% of young fleas and 96% of adult fleas

Suction

The suction is the maximum pressure difference that the pump can create. For example, a typical

domestic model has a suction of about negative 20 kPa. This means that it can lower the

pressure inside the hose from normal atmospheric pressure (about 100 kPa) by 20 kPa.

1. The electric current

operates themotor. The motor is attached to thefan, which has angled blades (like

anairplane propeller).

2. As the fan blades turn, they force air forward, toward the exhaust port(check out How

Airplanes Work to find out what causes this).

3. When air particles are driven forward, the density of particles (and therefore the air

pressure) increases in front of the fan and decreases behind the fan.

This pressure drop behind the fan is just like the pressure drop in the straw when you sip from

your drink. The pressure level in the area behind the fan drops below the pressure level outside

the vacuum cleaner (theambient air pressure). This creates suction, a partial vacuum, inside

the vacuum cleaner. The ambient air pushes itself into the vacuum cleaner through the intake

port because the air pressure inside the vacuum cleaner is lower than the pressure outside.

As long as the fan is running and the passageway through the vacuum cleaner remains open,

there is aconstant stream of air moving through the intake port and out the exhaust port. But

how does a flowing stream of air collect the dirt and debris from your carpet? The key principle

is friction.

18 calculatorAn electronic calculator is a small, portable, usually inexpensive electronic machine used to perform the basic operations of arithmetic. 

Modern electronic calculators contain a keyboard with buttons for digits and arithmetical operations. Some even contain 00 and 000 buttons to make large numbers easier to enter

WORKING!

[3] In general, a basic electronic calculator consists of the following components:

Power source (battery and/or solar cell)

Keypad - consists of keys used to input numbers and function commands (addition,

multiplication, square-root, etc.)

Processor chip (microprocessor) contains:

Scanning unit - when a calculator is powered on, it scans the keypad waiting to

pick up an electrical signal when a key is pressed.

Encoder  unit - converts the numbers and functions into binary code.

X register and Y register - They are number stores where numbers are stored

temporarily while doing calculations. All numbers go into the X register first. The number

in the X register is shown on the display.

Flag register - The function for the calculation is stored here until the calculator

needs it.

Permanent memory (ROM)- The instructions for in-built functions (arithmetic

operations, square roots, percentages, trigonometry etc.) are stored here in binary form.

These instructions are "programs" stored permanently. Permanent memory cannot be

erased.

User memory (RAM) - The store where numbers can be stored by the user.

User memory contents can be changed or erased by the user.

Arithmetic logic unit  (ALU) - The ALU executes all arithmetic and logic

instructions, and provides the results in binary coded form.

Decoder  unit - converts binary code into "decimal" numbers which can be

displayed on the display unit.

Display panel - displays input numbers, commands and results. Seven stripes

(segments) are used to represent each digit in a basic calculator.

[edit]Example

A basic explanation as to how calculations are performed in a simple 4-function calculator: To

perform the calculation 25 + 9, one presses keys in the following sequence on most calculators:

[2] [5] [+] [9] [=].

When 25 is entered, it is picked up by the scanning unit, the number 25 is encoded

and sent to the X register.

Next, when the [+] key is pressed, the "addition" instruction is also encoded and sent

to the flag register.

The second number 9 is encoded and sent to the X register. This "pushes" the first

number (25) out into the Y register.

When [=] is pressed, a "message" from the flag register tells the permanent memory

that the operation to be done is "addition".

The numbers in the X and Y registers are then loaded into the ALU and the

calculation is carried out following instructions from the permanent memory.

The answer, 34 is sent back to the X register. From there it is converted by the

decoder unit into a decimal number (usually binary-coded decimal), and then shown

on the display panel.

All other functions are usually carried out using repeated additions. Where calculators have

additional functions such as square root, or trigonometric functions, software algorithms are

required to produce high precision results. Sometimes significant design effort is required to

fit all the desired functions in the limited memory space available in the calculator chip, with

acceptable calculation time.[4]

make flow chart and diagram

19 ELECTROPLATING

Electroplating is a plating process in which metal ions in a

solution are moved by an electric field to coat an electrode. The process uses

electrical current to reduce cations of a desired material from a solution and coat

a conductive object with a thin layer of the material, such as a metal. Electroplating is primarily

used for depositing a layer of material to bestow a desired property (e.g., abrasion and wear

resistance,corrosion protection, lubricity, aesthetic qualities, etc.) to a surface that otherwise lacks

that property. Another application uses electroplating to build up thickness on undersized parts.

The process used in electroplating is called electrodeposition. It is analogous to a galvanic

cell acting in reverse. The part to be plated is thecathode of the circuit. In one technique,

the anode is made of the metal to be plated on the part. Both components are immersed in

a solutioncalled an electrolyte containing one or more dissolved metal salts as well as

other ions that permit the flow of electricity. A power supplysupplies a direct current to the anode,

oxidizing the metal atoms that comprise it and allowing them to dissolve in the solution. At the

cathode, the dissolved metal ions in the electrolyte solution are reduced at the interface between

the solution and the cathode, such that they "plate out" onto the cathode. The rate at which the

anode is dissolved is equal to the rate at which the cathode is plated, vis-a-vis the current flowing

through the circuit. In this manner, the ions in the electrolyte bath are continuously replenished by

the anode.[1]

PROCESSThe anode and cathode in the electroplating cell are both connected to an external supply of

direct current — a battery or, more commonly, a rectifier. The anode is connected to the positive

terminal of the supply, and the cathode (article to be plated) is connected to the negative terminal.

When the external power supply is switched on, the metal at the anode is oxidized from the

zero valence state to form cations with a positive charge. These cations associate with

the anions in the solution. The cations are reduced at the cathode to deposit in the metallic, zero

valence state. For example, in an acid solution, copper is oxidized at the anode to Cu2+ by losing

two electrons. The Cu2+ associates with the anion SO42- in the solution to form copper sulfate. At

the cathode, the Cu2+ is reduced to metallic copper by gaining two electrons. The result is the

effective transfer of copper from the anode source to a plate covering the cathode.

The plating is most commonly a single metallic element, not an alloy. However, some alloys can

be electrodeposited, notably brass andsolder.

Applications: fake jewellary

20PRESSURE COOKERSPressure cooking is a method of cooking in a sealed vessel that does not permit air or liquids to

escape below a preset pressure. Because the boiling point of water increases as

the pressure increases, the pressure built up inside the cooker allows the liquid in the pot to rise

to a higher temperature before boiling.

Pressure is created at the beginning with boiling liquid, such as water, inside the closed pressure

cooker and the trapped steam increases the internal pressure and temperature, which is

maintained throughout cooking time.

Design

Pressure cookers are generally made from aluminum or stainless steel. 

In most models a gasket or sealing ring forms a gas-tight seal which does not allow air or steam to escape between the pot and the lid, other more expensive models feature a metal to metal seal. Normally, the only way the steam can escape is through a regulator on the lid when the pressure has built up. In case the regulator is blocked, a safety valve is provided as a backup escape route for steam. The simplest safety valve is a loose-fitting rubber plug in the lid, held in place by steam pressure. If the pressure exceeds design limits, the plug pops out of its seat.

Operation

The food to be cooked is placed in the pressure cooker, with a small amount of water or liquid

required for the recipe. The lid is closed, the pressure setting selected and the pressure cooker is

placed on a heat source, e.g., a stove, at the highest heat (if a weight is used, the weight is

placed on the steam vent when steam is being emitted, as this ensures the air inside has

escaped) until the cooker reaches full pressure, then the heat is lowered to maintain pressure and

timing the recipe begins at this point. A common mistake is for the user to start timing the recipe

when the pop-up indicator rises as soon as there is the slightest amount of pressure in the

cooker, instead of timing the recipe when the cooker has reached its selected pressure level.

Some pressure cookers have markers on the pop-up indicator which show the pressure level, but

normally the pop-up indicator just shows that the cooker has pressure inside, which is not a

reliable means of showing that the cooker has reached its selected pressure. This indicator also

acts as an interlock to prevent the lid being opened when there is any pressure inside.

Advantages

Foods are cooked much faster by pressure cooking than by other methods (except for small

quantities in microwave ovens), and with much less water used than boiling, so dishes can be

ready sooner. Less energy is required than when boiling, steaming or oven cooking. Since less

water is necessary, the foods come to cooking temperature faster.

The pressure cooker speeds cooking considerably at high altitudes, where the low atmospheric

pressure otherwise reduces the boiling point of water, which reduces water's effectiveness for

cooking or preparing hot drinks.

[edit]Disadvantages

Pressure cookers are considerably more expensive than conventional saucepans of the same

size. The additional gasket requires special care when cleaning, unlike a standard lid for a

saucepan

21 BATTERYAn electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy.[1] Since the invention of the first battery (or "voltaic pile") in 1800 by Alessandro Volta, batteries have become a common power source for many household and industrial applicationsThere are two types of batteries: primary batteries (disposable batteries), which are designed to be used once and discarded, and secondary batteries (rechargeable batteries), which are designed to be recharged and used multiple times. Batteries come in many sizes, from miniature cells used to power hearing aids and wristwatches to battery banks the size of rooms that provide standby power for telephone exchanges and computer data centers.

A battery is a device that converts chemical energy directly

to electrical energy.[22] It consists of a number of voltaic cells; each voltaic cell consists of two half

cells connected in series by a conductive electrolyte containing anions and cations. One half-cell

includes electrolyte and the electrode to which anions (negatively charged ions) migrate, i.e.,

the anode or negative electrode; the other half-cell includes electrolyte and the electrode to

which cations (positively charged ions) migrate, i.e., the cathode or positive electrode. In

the redox reaction that powers the battery, cations are reduced (electrons are added) at the

cathode, while anions are oxidized (electrons are removed) at the anode.[23] The electrodes do not

touch each other but are electrically connected by the electrolyte. Some cells use two half-cells

with different electrolytes. A separator between half cells allows ions to flow, but prevents mixing

of the electrolytes.

Each half cell has an electromotive force (or emf), determined by its ability to drive electric current

from the interior to the exterior of the cell. The net emf of the cell is the difference between the

emfs of its half-cells, as first recognized by Volta.[12] Therefore, if the electrodes have emfs  

and  , then the net emf is  ; in other words, the net emf is the difference between

the reduction potentials of the half-reactions.[24]

APPLICATIONS!!!

22 ARC WELDINGArc welding is a type of welding that uses a welding power supply to create an electric arc between an electrode and the base material to melt the metals at the welding point. They can use either direct (DC) or alternating (AC) current, and consumable or non-consumable electrodes. The welding region is usually protected by some type of shielding gas, vapor, and/or slag.

POWER SUPPLY

To supply the electrical energy necessary for arc welding processes, a number of different power

supplies can be used. The most common classification is constant current power supplies and

constant voltage power supplies. In arc welding, the voltage is directly related to the length of the

arc, and the current is related to the amount of heat input. Constant current power supplies are

most often used for manual welding processes such as gas tungsten arc welding and shielded

metal arc welding, because they maintain a relatively constant current even as the voltage varies.

This is important because in manual welding, it can be difficult to hold the electrode perfectly

steady, and as a result, the arc length and thus voltage tend to fluctuate. Constant voltage power

supplies hold the voltage constant and vary the current, and as a result, are most often used for

automated welding processes such as gas metal arc welding, flux cored arc welding, and

submerged arc welding. In these processes, arc length is kept constant, since any fluctuation in

the distance between the wire and the base material is quickly rectified by a large change in

current. For example, if the wire and the base material get too close, the current will rapidly

increase, which in turn causes the heat to increase and the tip of the wire to melt, returning it to

its original separation distance.[13]

The direction of current used in arc welding also plays an important role in welding. Consumable

electrode processes such as shielded metal arc welding and gas metal arc welding generally use

direct current, but the electrode can be charged either positively or negatively. In welding, the

positively charged anode will have a greater heat concentration and, as a result, changing the

polarity of the electrode has an impact on weld properties. If the electrode is positively charged, it

will melt more quickly, increasing weld penetration and welding speed. Alternatively, a negatively

charged electrode results in more shallow welds.[14] Non-consumable electrode processes, such

as gas tungsten arc welding, can use either type of direct current (DC), as well as alternating

current (AC). With direct current however, because the electrode only creates the arc and does

not provide filler material, a positively charged electrode causes shallow welds, while a negatively

charged electrode makes deeper welds.[15]Alternating current rapidly moves between these two,

resulting in medium-penetration welds. 

APPLIC ATIONS!!

23 ECLIPSE

The progression of a lunar eclipse. Totality is shown with the last two images to lower right. These required a

longer exposure time to make the details visible.

An eclipse is an astronomical event that occurs when an astronomical object is temporarily

obscured, either by passing into the shadow of another body or by having another body pass

between it and the viewer. An eclipse is a type of syzygy.[1]

The term eclipse is most often used to describe either a solar eclipse, when the Moon's shadow

crosses the Earth's surface, or a lunar eclipse, when the Moon moves into the Earth's shadow.

However, it can also refer to such events beyond the Earth-Moon system: for example, a planet

moving into the shadow cast by one of its moons, a moon passing into the shadow cast by its

host planet, or a moon passing into the shadow of another moon. A binary star system can also

produce eclipses if the plane of the orbit of its constituent stars intersects the observer's position.

Umbra, penumbra and antumbra

Umbra, penumbra and antumbra cast by a solid object occulting a larger light source.

The region of the Earth's shadow in a solar eclipse is divided into three parts[5]:

The umbra, within which the Moon completely covers the Sun (more precisely, its

photosphere)

The antumbra, extending beyond the tip of the umbra, within which the Moon is

completely in front of the Sun but too small to completely cover it

The penumbra, within which the Moon is only partially in front of the Sun

During a lunar eclipse only the umbra and penumbra are applicable. This is because Earth's

apparent diameter from the viewpoint of the Moon is nearly 4 times that of the Sun.

The first contact occurs when the Moon's disc first starts to impinge on the Sun's; second

contact is when the Moon's disc moves completely within the Sun's; third contact when it starts to

move out of the Sun's; and fourth or last contact when it finally leaves the Sun's disc entirely.

EARTH MOON SYSTEMAn eclipse involving the Sun, Earth and Moon can occur only when they are nearly in a straight line, allowing one to be hidden behind another, viewed from the third. Because the orbital plane of the Moon is tilted with respect to the orbital plane of the Earth (the ecliptic), eclipses can occur only when the Moon is close to the intersection of these two planes (the nodes). The Sun, Earth and nodes are aligned twice a year (during an eclipse season), and eclipses can occur during a period of about two months around these times. There can be from four to seven eclipses in a calendar year, which repeat according to various eclipse cycles, such as a saros.

A solar eclipse occurs when the Moon passes in front of the Sun as seen from the Earth.Lunar eclipses occur when the Moon passes through the Earth's shadow. Since this occurs only when the Moon is on the far side of the Earth from the Sun, lunar eclipses only occur when there is a full moon.

24 GEOSTATIONARY SATELLITESA geosynchronous Satellite is a satellite whose orbit on the Earth repeats regularly over points on the Earth over time. If such a satellite's orbit lies over the equator, the orbit is circular and its angular velocity is the same as the earth's, then it is called a geostationary satellite.

Application

There are approximately 300 operational geosynchronous satellites.

Geostationary satellites appear to be fixed over one spot above the equator. Receiving and

transmitting antennas on the earth do not need to track such a satellite. These antennas can be

fixed in place and are much less expensive than tracking antennas. These satellites have

revolutionized global communications, television broadcasting and weather forecasting, and have

a number of important defense and intelligence applications.

One disadvantage of geostationary satellites is a result of their high altitude: radio signals take

approximately 0.25 of a second to reach and return from the satellite, resulting in a small but

significant signal delay. This delay increases the difficulty of telephone conversation and reduces

the performance of common network protocols such as TCP/IP, but does not present a problem

with non-interactive systems such as television broadcasts. There are a number of proprietary

satellite data protocols that are designed to proxy TCP/IP connections over long-delay satellite

links—these are marketed as being a partial solution to the poor performance of native TCP over

satellite links. TCP presumes that all loss is due to congestion, not errors, and probes link

capacity with its "slow-start" algorithm, which only sends packets once it is known that earlier

packets have been received. Slow start is very slow over a path using a geostationary satellite.

Another disadvantage of geostationary satellites is the incomplete geographical coverage, since

ground stations at higher than roughly 60 degrees latitude have difficulty reliably receiving signals

at low elevations. Satellite dishes at such high latitudes would need to be pointed almost directly

towards the horizon. The signals would have to pass through the largest amount of atmosphere,

and could even be blocked by land topography, vegetation or buildings. In the USSR, a practical

solution was developed for this problem with the creation of specialMolniya / Orbita inclined path

satellite networks with elliptical orbits. Similar elliptical orbits are used for the Sirius

Radio satellites.

ELABORATE ON APPLICATIONS

25FLUOROSCENT LAMPA fluorescent lamp or fluorescent tube is a gas-discharge lamp that

uses electricity to excite mercury vapor. The excited mercury atoms produce short-

wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light. A

fluorescent lamp converts electrical power into useful light more efficiently than an incandescent

lamp. Lower energy cost typically offsets the higher initial cost of the lamp. The lamp fixture is

more costly because it requires a ballast to regulate the current through the lamp.

While larger fluorescent lamps have been mostly used in commercial or institutional buildings,

the compact fluorescent lamp is now available in the same popular sizes as incandescents and is

used as an energy-saving alternative in homes.

A preheat fluorescent lamp circuit using an automatic starting switch. A: Fluorescent tube, B: Power (+220 volts),

C: Starter, D: Switch (bi-metallic thermostat), E: Capacitor, F: Filaments, G: Ballast

Principles of operation

The fundamental means for conversion of electrical energy into radiant energy in a fluorescent

lamp relies on inelastic scattering of electrons. An incident electron collides with an atom in the

gas. If the free electron has enough kinetic energy, it transfers energy to the atom's outer

electron, causing that electron to temporarily jump up to a higher energy level. The collision is

'inelastic' because a loss of energy occurs.

This higher energy state is unstable, and the atom will emit an ultraviolet photon as the atom's

electron reverts to a lower, more stable, energy level. Most of the photons that are released from

the mercury atoms have wavelengths in the ultraviolet (UV) region of the spectrum,

predominantly at wavelengths of 253.7 and 185 nanometers (nm). These are not visible to the

human eye, so they must be converted into visible light. This is done by making use

of fluorescence. Ultraviolet photons are absorbed by electrons in the atoms of the lamp's interior

fluorescent coating, causing a similar energy jump, then drop, with emission of a further photon.

The photon that is emitted from this second interaction has a lower energy than the one that

caused it. The chemicals that make up the phosphor are chosen so that these emitted photons

are at wavelengths visible to the human eye. The difference in energy between the absorbed

ultra-violet photon and the emitted visible light photon goes toward heating up the phosphor

coating.

When the light is turned on, the electric power heats up the cathode enough for it to emit

electrons (thermionic emission). These electrons collide with and ionize noble gas atoms inside

the bulb surrounding the filament to form a plasma by the process of impact ionization. As a result

of avalanche ionization, the conductivity of the ionized gas rapidly rises, allowing higher currents

to flow through the lamp.

Advantages

[edit]Luminous efficacy

Fluorescent lamps convert more of the input power to visible light than incandescent lamps.

Life

Typically a fluorescent lamp will last between 10 to 20 times as long as an equivalent

incandescent lamp when operated several hours at a time.

The higher initial cost of a fluorescent lamp is usually more than compensated for by lower

energy consumption over its life.[28] The longer life may also reduce lamp replacement costs,

providing additional saving especially where labor is costly. Therefore they are widely used by

businesses and institutions, but not as much by households.

[edit]Lower luminosity

Compared with an incandescent lamp, a fluorescent tube is a more diffuse and physically larger

light source. In suitably designed lamps, light can be more evenly distributed without point source

of glare such as seen from an undiffused incandescent filament; the lamp is large compared to

the typical distance between lamp and illuminated surfaces.

[edit]Lower heat

About two-thirds to three-quarters less heat is given off by fluorescent lamps compared to an

equivalent installation of incandescent lamps. This greatly reduces the size, cost, and energy

consumption.

Disadvantages

Frequent switching

Health and safety issues

Main article: Fluorescent lamps and health

If a fluorescent lamp is broken, a very small amount of mercury can contaminate the surrounding

environment

Ultraviolet emission

Fluorescent lamps emit a small amount of ultraviolet (UV) light

26 INTERNETThe Internet is a global system of interconnected computer networks that use the

standard Internet protocol suite (TCP/IP) to serve billions of users worldwide. It is a network of

networks that consists of millions of private, public, academic, business, and government

networks, of local to global scope, that are linked by a broad array of electronic, wireless and

optical networking technologies. The Internet carries a vast range of information resources and

services, such as the inter-linked hypertext documents of the World Wide Web(WWW) and

the infrastructure to support electronic mail.

Most traditional communications media including telephone, music, film, and television are

reshaped or redefined by the Internet, giving birth to new services such as Voice over Internet

Protocol (VoIP) and IPTV. Newspaper, book and other print publishing are adapting toWeb

site technology, or are reshaped into blogging and web feeds. The Internet has enabled or

accelerated new forms of human interactions through instant messaging, Internet forums,

and social networking. Online shopping has boomed both for major retail outlets and

small artisans and traders. Business-to-business and financial services on the Internet

affect supply chains across entire industries.

The origins of the Internet reach back to research of the 1960s, commissioned by the United

States government in collaboration with private commercial interests to build robust, fault-tolerant,

and distributed computer networks. The funding of a new U.S. backbone by theNational Science

Foundation in the 1980s, as well as private funding for other commercial backbones, led to

worldwide participation in the development of new networking technologies, and the merger of

many networks. The commercialization of what was by the 1990s an international network

resulted in its popularization and incorporation into virtually every aspect of modern human life.

As of 2011, more than 2.1 billion people – nearly a third of Earth's population – use the services

of the Internet.[1]

The Internet has no centralized governance in either technological implementation or policies for

access and usage; each constituent network sets its own standards. Only the overreaching

definitions of the two principal name spaces in the Internet, the Internet Protocol address space

and the Domain Name System, are directed by a maintainer organization, the Internet

Corporation for Assigned Names and Numbers (ICANN). The technical underpinning and

standardization of the core protocols (IPv4 and IPv6) is an activity of the Internet Engineering

Task Force (IETF), a non-profit organization of loosely affiliated international participants that

anyone may associate with by contributing technical expertise.

APPLICATIONS!!!