TECHNICAL DESCRIPTION

1. Water spring

Geyser activity, like all hot spring activity, is caused by surface water gradually seeping down through the ground until it meets rock heated by magma. The geothermally heated water then rises back toward the surface by convection through porous and fractured rock. Geysers differ from noneruptive hot springs in their subterranean structure; many consist of a small vent at the surface connected to one or more narrow tubes that lead to underground reservoirs of water.

As the geyser fills, the water at the top of the column cools off, but because of the narrowness of the channel, convective cooling of the water in the reservoir is impossible. The cooler water above presses down on the hotter water beneath, not unlike the lid of a pressure cooker, allowing the water in the reservoir to become superheated, i.e. to remain liquid at temperatures well above the boiling point.

Ultimately, the temperatures near the bottom of the geyser rise to a point where boiling begins; steam bubbles rise to the top of the column. As they burst through the geyser's vent, some water overflows or splashes out, reducing the weight of the column and thus the pressure on the water underneath. With this release of pressure, the superheated water flashes into steam, boiling violently throughout the column. The resulting froth of expanding steam and hot water then sprays out of the geyser hole.

Eventually the water remaining in the geyser cools back to below the boiling point and the eruption ends; heated groundwater begins seeping back into the reservoir, and the whole cycle begins again. The duration of eruptions and time between successive eruptions vary greatly from geyser to geyser; Strokkur in Iceland erupts for a few seconds every few minutes, while Grand Geyser in the U.S. erupts for up to 10 minutes every 812 hours. Old Faithful, perhaps the best-known geyser at Yellowstone National Park, is an example of a cone geyser. The intense transient forces inside erupting geysers are the main reason for their rarity. There are many volcanic areas in the world that have hot springs, mud pots and fumaroles, but very few with geysers. This is because in most places, even where other necessary conditions for geyser activity exist, the rock structure is loose, and eruptions will erode the channels and rapidly destroy any nascent geysers. Geysers are fragile phenomena and if conditions change, they can die. Many geysers have been destroyed by people throwing litter and debris into them; others have ceased to erupt due to dewatering by geothermal power plants. The Great Geyser of Iceland has had periods of activity and dormancy. During its long dormant periods, eruptions were sometimes humanly-induced often on special occasions by the addition of surfactants to the water. Inducing eruptions at Geyser is no longer done, as the forced eruptions were damaging the geyser's special plumbing system. Following an earthquake in Iceland in 2000 the geyser became somewhat more active again.

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Initially the geyser erupted about eight times a day. As of July 2003, Geyser erupts several times a week.

2. Television

The elements of a simple broadcast television system are:

An image source. This is the electrical signal representing the visual image, and may be from a camera in the case of live images, a video tape recorder for playback of recorded images, or a film chain-telecine-flying spot scanner for transmission of motion pictures (films).

A sound source. This is an electrical signal from a microphone or from the audio output of a video tape recorder or motion picture film scanner.

A transmitter, which generates radio signals (radio waves) and encodes them with picture and sound information.

An antenna coupled to the output of the transmitter for broadcasting the encoded signals.

An antenna to receive the broadcast signals. A receiver (also called a tuner), which decodes the picture and sound

information from the broadcast signals, and whose input is coupled to the antenna.

A display device, which turns the electrical signals into visual images. An audio amplifier and loudspeaker, which turns electrical signals into

sound waves (speech, music, and other sounds) to accompany the images.

3. Pressure Cooker

Pressure cooking is a method of cooking in a sealed vessel that does not permit air or liquids to escape below a preset pressure. Because water's boiling point increases as the pressure increases, the pressure built up inside the cooker allows the liquid in the pot to rise to a temperature higher than 100 C (212F) before boiling.

The materials used for making cookers are generally aluminum and stainless steel. The former may be stamped and buffed or anodized, but this metal is unsuitable for the dishwasher. Expensive stainless steel pressure cookers are made with heavy, three-ply, or copper-clad bottoms for uniform heating. Most modern units are dishwasher safe, although some manufacturers may recommend washing by hand. A gasket forms an airtight seal which does not allow air or steam to escape between the pan and the lid, the only way the steam can escape is through a regulator on the lid when the pressure has built up (or if the regulator is blocked, through a safety valve). Sometimes the gasket is referred to as a sealing ring.

4. Electric Fan

Table fan - Basic elements of a typical table fan include the fan blade, base, armature and lead wires, motor, blade guard, motor housing, oscillator gearbox, and oscillator shaft. The oscillator is a mechanism that motions the fan from side to side. The axle comes out on both ends of the motor, one end

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of the axle is attached to the blade and the other is attached to the oscillator gearbox. The motor case joins to the gearbox to contain the rotor and stator. The oscillator shaft combines to the weighted base and the gearbox. A motor housing covers the oscillator mechanism. The blade guard joins to the motor case for safety.

Electro-mechanical fans, among collectors, are rated according to their condition, size, age, and number of blades. Four-blade designs are the most common. Five-blade or six-blade designs are rare. The materials from which the components are made, such as brass, are important factors in fan desirability.

A fan suspended from the ceiling of a room is a ceiling fan. In automobiles, a mechanical fan, driven with a belt and pulley off the

engine's crankshaft, or an electric fan switched on/off by a thermo switch is used to blow or suck air through a coolant filled radiator, to prevent the engine from overheating.

Computer fan

5. Volcano

A volcano is an opening, or rupture, in a planet's surface or crust, which allows hot, molten rock, ash and gases to escape from below the surface. Volcanic activity involving the extrusion of rock tends to form mountains or features like mountains over a period of time.

Volcanoes are generally found where tectonic plates pull apart or come together. 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 (called "non-hotspot intraplate volcanism"), such as in the African Rift Valley, the Wells Gray-Clearwater Volcanic

The most common perception of a volcano is of a conical mountain, spewing lava and poisonous gases from a crater at its summit. This describes just one of many types of volcano, and the features of volcanoes are much more complicated. The structure and behavior of volcanoes depends on a number of factors. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater, whereas others present landscape features such as massive plateaus. Vents that issue volcanic material (lava, which is what magma is called once it has escaped to the surface, and ash) and gases (mainly steam and magmatic gases) can be located anywhere on the landform. Many of these vents give rise to smaller cones such as Puu on a flank of Hawaii's Klauea.

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Indonesia - Lombok: Mount Rinjani - outbreak in 1995

Other types of volcano include cryovolcanoes (or ice volcanoes), particularly on some moons of Jupiter, Saturn and Neptune; and mud volcanoes, which are formations often not associated with known magmatic activity. Active mud volcanoes tend to involve temperatures much lower than those of igneous volcanoes, except when a mud volcano is actually a vent of an igneous volcano

6. AIR CONDITIONER

An air conditioner is an appliance, system, or mechanism designed to extract heat from an area using a refrigeration cycle. In construction, a complete system of heating, ventilation, and air conditioning is referred to as HVAC. Its purpose, in the home or in the car, is to provide comfort during hot days and nights.

Refrigeration cycle

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

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 into the room in which it stands.

This cycle takes advantage of the universal gas law PV = nRT, where P is pressure, V is volume, R is the universal gas constant, T is temperature, and n is the number of moles of gas (1 mole = 6.0221023 molecules).

The most common refrigeration cycle uses an electric motor to drive a compressor. In an automobile the compressor is driven by a pulley on the engine's crankshaft, with both using electric motors for air circulation. Since evaporation occurs when heat is absorbed, and condensation occurs when heat is released, air conditioners are designed to use a compressor to cause pressure changes between two compartments, and actively pump a refrigerant around. A refrigerant is pumped into the cooled compartment (the evaporator coil), where the low pressure and low temperature cause the refrigerant to evaporate into a vapor, taking heat with it. In the other compartment (the condenser), the refrigerant vapour is compressed and forced through another heat exchange coil, condensing into a liquid, rejecting the heat previously absorbed from the cooled space.

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7. IRONING

Ironing or smoothing is the work of using a heated tool to remove wrinkles from washed clothes. The common tools for this purpose are called "irons", though modern designs are no longer made of iron.

Ironing works by loosening the bonds between the long-chain polymer molecules in the fibres of the material. While the molecules are hot, the fibres are straightened by the weight of the iron, and they hold their new shape as they cool. Some fabrics, such as cotton, require the addition of water to loosen the intermolecular bonds. Many modern fabrics (developed in or after the mid-twentieth century) are advertised as needing little or no ironing.

Ironing may also be used as a germ/parasite killing hygienic operation.

Modern ironing equipment

Home irons are normally classified into automatic and non-automatic irons. An entirely different device, a steam press, is used by commercial laundry and dry-cleaning services.

Manual home irons

Modern irons available for sale to consumers have some or all of the following features (more expensive models have more features, as one would expect):

Ejection of steam through the clothing during the ironing process; A water reservoir inside the iron (used for the steam generation); An indicator showing the amount of water left in the reservoir; A thermostat ensuring maintenance of a constant temperature; Convenient method for setting the iron down, usually on its end / vertically, so

as to not allow contact between the hot part and either table or clothes; A temperature control dial showing a range of possible temperatures (typically

marked with types of cloth instead of absolute degree measurements, for example, "wool", "cotton", "linen", etc.);

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

Cord control - the point at which the cord attaches to the iron has a spring to hold the cord out of the way while ironing and likewise when setting down the iron (prevents fires, is more convenient, etc.).

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

(advanced feature) Dial controlling the amount of steam to emit as a constant stream;

(advanced feature) Anti-burn control - if the iron is left flat (hot part touching clothes) for too long, the iron shuts off to prevent fires;

(advanced feature) Energy saving control - if the iron is left undisturbed for several (10 or 15) minutes, the iron shuts off to save energy and prevent fires.

Cordless irons - the iron is placed on a stand for a short period to warm up, using thermal mass to stay hot for a short period. These are useful for light

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loads only. (Unlike other cordless appliances, cordless irons are not powered from rechargeable batteries, because it would be difficult for batteries to provide enough power to heat the iron.)

(advanced feature) 3 way auto shut off (advanced feature) self-cleaning (advanced feature) Anti-drip system Electrical cord with Teflon (PTFE) insulation.

Automatic ironing robots and major home appliances

Automatic ironing robots, like the Siemens AG Dressman (see link below), have recently appeared on the market.

Automatic ironing (major) home appliances: Driron.

USES

Irons are commonly available as consumer goods. Some commercial-grade irons have a boiler unit separate from the handheld iron. Most ironing is done on an ironing board, a small, portable, foldable table with a heat resistant top.Some commercial-grade ironing boards incorporate a heating element and a pedal-operated vacuum to pull air through the board and dry the garment.

Permanent press clothing was developed to reduce the ironing necessary by combining wrinkle-resistant polyester with cotton.

Commercial laundries typically use steam presses to iron clothes instead of irons;

Clothes such as shirts, trousers, and skirts are typically ironed, while underwear, socks, sheets, sweaters, and materials where wrinkling is not a factor are not, although this depends on the culture and circumstances.

Irons cause many fires and injuries each year due to their being very heavy, very hot, and often used on ironing boards that can fall over onto small children.

Irons used to be much more dangerous due to the electrical cords fraying; modern insulation is much safer and better able to cope with being heated

8. Dry Cell

dry cell is a galvanic electrochemical cell with a pasty low-moisture electrolyte For the cheapest carbon-zinc variety, a zinc outer casing (anode) contains a layer of NH4Cl with ZnCl2 aqueous paste separated by a paper layer from a mixture of powdered carbon & [[manganese(IV) oxide]=] (MnO2) which is packed around a carbon rod (cathode). As the cell runs, manganese is reduced from an oxidation state of +4 to +3, collecting electrons from the carbon rod, while the zinc metal anode is oxidized to Zn2+ ions, producing the electrons. So the electrons travel outside the cell, from the zinc casing (the negative end or anode) through contacts and wires to the carbon rod (which is in contact with the manganese dioxide powder, the actual cathode material, and so is positive).

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In so-called alkaline cells (see alkaline battery), some of the electrolyte in the paste is replaced with an alkaline paste of potassium hydroxide. However, the essential transfer of electrons from zinc to manganese still powers the cell.

The standard carbon-zinc dry cell is relatively cheap, and until recently, has been the most common type of cell (only recently being replaced in most uses by the alkaline type). It was the first commercial portable battery (technically, a battery is made of two or more cells) and therefore the dry cell had a large impact on society, as it contributed to the development of flashlights (torches) and portable radios.

9. VACCUM CLEANER

A vacuum cleaner (in colloquial British English also hoover[1]) is a device that uses an air pump to create a partial vacuum to suck up dust and dirt, usually from floors. Most homes with carpeted floors in developed countries possess a vacuum cleaner for cleaning. The dirt is collected by a filtering system or a cyclone for later disposal

A vacuum's suction is caused by a difference in air pressure. A pump reduces the pressure inside the tube. Atmospheric pressure then pushes the air through the carpet and into the tube, and so the dust is literally pushed into the bag.

The first manually-powered cleaner using vacuum principles was the "Whirlwind", invented in Chicago in 1868 by Ives W. McGaffey. The machine was lightweight and compact, but was difficult to operate because of the need to turn a hand crank at the same time as pushing it across the floor. McGaffey obtained a patent for his device on June 5, 1869, and enlisted the help of The American Carpet Cleaning Co. of Boston to market it to the public. It was sold for $25, a high price in those days. It is hard to determine how successful the Whirlwind was, as most of them were sold in Chicago and Boston, and it is likely that many were lost in the Great Chicago Fire of 1871. Only two are known to have survived, one of which can be found in the Hoover Historical Center.

McGaffey was but one of many 19th-century inventors in the United States and Europe who devised manual vacuum cleaners. The first patent for an electrically driven "carpet sweeper and dust gatherer" was granted to Corinne Dufour of Savannah, Georgia in December 1900.

10.MICROWAVE OVEN

microwave oven, or microwave, is a kitchen appliance employing microwave radiation primarily to cook or heat food. Microwave ovens have revolutionized food preparation since their use became widespread in the 1970s.

A microwave oven consists of:

a high voltage transformer, which passes energy to the magnetron a cavity magnetron, a magnetron control circuit (usually with a microcontroller), a waveguide, and a cooking chamber

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A microwave oven works by passing nonionizing microwave radiation, usually at a frequency of 2.45 GHz (a wavelength of 12.24 cm), 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 heating. Many molecules (such as those of water) are electric dipoles, meaning that they have a positive charge at one end and a negative charge at the other, and therefore rotate as they try to align themselves with the alternating electric field induced by the microwaves. This molecular movement creates heat as the rotating molecules hit other molecules and put them into motion. Microwave heating is most efficient on liquid water, and much less so on fats and sugars (which have less molecular dipole moment), and frozen water (where the molecules are not free to rotate). Microwave heating is sometimes explained as a rotational resonance of water molecules, but this is incorrect: such resonance only occurs in water vapour at much higher frequencies, at about 20 gigahertz.

A common misconception is that microwave ovens cook food from the "inside out". In reality, microwaves are absorbed in the outer layers of food in a manner somewhat similar to heat from other methods. The misconception arises because microwaves penetrate dry nonconductive substances at the surfaces of many common foods, and thus often deposit initial heat more deeply than other methods. Depending on water content, the depth of initial heat deposition may be several centimeters or more with microwave ovens, in contrast to broiling (infrared) or convection heating, which deposit heat thinly at the food surface. Depth of penetration of microwaves is dependent on food composition and the frequency, with lower microwave frequencies penetrating better.

Most microwave ovens allow the user to choose between several power levels, including one or more defrosting levels. In most ovens, however, there is no change in the intensity of the microwave radiation; instead, the magnetron is turned on and off in cycles of several seconds at a time. This can actually be observed when microwaving airy foods which may inflate during heating phases, and deflate when the magnetron is turned off. Newer models have inverter power supplies which provide truly continuous low-power microwave heating.

The cooking chamber itself is a Faraday cage enclosure which prevents the microwaves from escaping into the environment. The oven door is usually a glass panel for easy viewing, but has a layer of conductive mesh to maintain the shielding. Because the size of the perforations in the mesh is much less than the wavelength of 12 cm, most of the microwave radiation cannot pass through the door, while visible light (with a much shorter wavelength) can. With wireless computer networks gaining in popularity, microwave interference has become a concern near wireless networks. Microwave ovens are capable of disrupting wireless network transmissions because the ovens generate radio waves of about 2.45 GHz in the 802.11b/g frequency band, some of them escaping the enclosure despite the presence of the mesh

11.FLOPPY DISK

A floppy disk is a data storage device that is composed of a disk of thin, flexible ("floppy") magnetic storage medium encased in a square or rectangular plastic shell. Floppy disks are read and written by a floppy disk drive or FDD, the initials of

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which should not be confused with "fixed disk drive", which is another term for a hard disk drive. Invented by IBM, floppy disks in 8", 5.25", and 3.5" formats enjoyed many years as a popular and ubiquitous form of data storage and exchange, from the middle 1970s to the late 1990s. However, they have now been largely superseded by Flash and optical storage devices while email has become the preferred method of exchanging small to medium digital files.

The 3-inch disk is made of two pieces of rigid plastic, with the fabric-medium-fabric sandwich in the middle to remove dust and dirt. The front has only a label and a small aperture for reading and writing data, protected by a spring-loaded metal cover, which is pushed back on entry into the drive.

The 3-inch floppy disk drive automatically engages when the user inserts a disk, and disengages and ejects with the press of the eject button. On Macintoshes with built-in floppy drives, the disk is ejected by a motor (similar to a VCR) instead of manually; there is no eject button. The disk's desktop icon is dragged onto the Trash icon to eject a disk.

The reverse has a similar covered aperture, as well as a hole to allow the spindle to connect into a metal plate glued to the medium. Two holes, bottom left and right, indicate the write-protect status and high-density disk correspondingly, a hole meaning protected or high density, and a covered gap meaning write-enabled or low density. (Incidentally, the write-protect and high-density holes on a 3-inch disk are spaced exactly as far apart as the holes in punched A4 paper (8 cm), allowing write-protected floppies to be clipped into European ring binders.) A notch top right ensures that the disk is inserted correctly, and an arrow top left indicates the direction of insertion. The drive usually has a button that, when pressed, will spring the disk out at varying degrees of force. Some would barely make it out of the disk drive; others would shoot out at a fairly high speed. In a majority of drives, the ejection force is provided by the spring that holds the cover shut, and therefore the ejection speed is dependent on this spring. In PC-type machines, a floppy disk can be inserted or ejected manually at any time (evoking an error message or even lost data in some cases), as the drive is not continuously monitored for status and so programs can make assumptions that do not match actual status (i.e., disk 123 is still in the drive and has not been altered by any other agency). With Apple Macintosh computers, disk

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drives are continuously monitored by the OS; a disk inserted is automatically searched for content and one is ejected only when the software agrees the disk should be ejected. This kind of disk drive (starting with the slim "Twiggy" drives of the late Apple "Lisa") does not have an eject button, but uses a motorized mechanism to eject disks; this action is triggered by the OS software (e.g. the user dragged the "drive" icon to the "trash can" icon). Should this not work (as in the case of a power failure or drive malfunction), one can insert a straight-bent paper clip into a small hole at the drive's front, thereby forcing the disk to eject (similar to that found on CD/DVD drives). Some other computer designs (such as the Commodore Amiga) monitor for a new disk continuously, but still have push-button eject mechanisms.

The 3-inch disk bears much similarity to the 3-inch type, with some unique and somehow curious features. One example is the rectangular-shaped plastic casing, almost taller than a 3-inch disk, but narrower, and more than twice as thick, almost the size of a standard compact audio cassette. This made the disk look more like a greatly oversized present day memory card or a standard PC card notebook expansion card rather than a floppy disk. Despite the size, the actual 3-inch magnetic-coated disk occupied less than 50% of the space inside the casing, the rest being used by the complex protection and sealing mechanisms implemented on the disks. Such mechanisms were largely responsible for the thickness, length and high costs of the 3-inch disks. On the Amstrad machines the disks were typically flipped over to use both sides, as opposed to being truly double-sided. Double-sided mechanisms were available but rare.

12.Telephone

The telephone is a telecommunications device which is used to transmit and receive sound (most commonly speech), usually two people conversing but occasionally three or more. It is one of the most common household appliances in the world today. Most telephones operate through transmission of electric signals over a complex telephone network which allows almost any phone user to communicate with almost anyone.

The telephone handles two types of information: signals and voice, at different times on the same twisted pair of wires. The signaling equipment consists of a bell to alert the user of incoming calls, and a dial to enter the phone number for outgoing calls. A calling party wishing to speak to another telephone will pick up the handset, thus operating the switch hook, which puts the telephone into active state or off hook with a resistance short across the wires, causing current to flow. The telephone exchange detects the DC current, attaches a digit receiver, and sends dial tone to indicate readiness. The user pushes the number buttons, which are connected to a tone generator inside the dial, which generates DTMF tones. The exchange connects the line to the desired line and alerts that line.

When a phone is inactive (on hook), its bell, beeper, flasher or other alerting device is connected across the line through a capacitor. The inactive phone does not short the line, thus the exchange knows it is on hook and only the bell is electrically connected. When someone calls this phone, the telephone exchange applies a high voltage pulsating signal, which causes the sound mechanism to ring, beep or otherwise alert the called party. When that user picks up the handset, the switchhook disconnects the bell, connects the voice parts of the telephone, and puts a resistance short on the line,

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confirming that the phone has been answered and is active. Both lines being off hook, the signaling job is complete. The parties are connected together and may converse using the voice parts of their telephones.

The voice parts of the telephone are in the handset, and consist of a transmitter (often called microphone) and a receiver. The transmitter, powered from the line, puts out an electric current which varies in response to the acoustic pressure waves produced by the voice. The resulting variations in electric current are transmitted along the telephone line to the other phone, where they are fed into the coil of the receiver, which is a miniature loudspeaker. The varying electric current in the coil causes it to move back and forth, reproducing the acoustic pressure waves of the transmitter.

When a party "hangs up" (puts the handset on the cradle), DC current ceases to flow in that line, thus signaling to the exchange switch to disconnect the telephone call

13.Electric bell

An electric bell is a mechanical bell that functions by means of an electromagnet.

In DC electric bells, when power is applied, current flows through the coil. The coil becomes an electromagnet, attracting the metal strip. This moves the clanger to hit the bell, but also breaks the circuit. The coil is no longer a magnet, so the clanger moves back. The circuit is thus restored. The process repeats continuously until the power is removed.

AC electric bells do not have interrupting contacts and their coils are powered directly by the source. Their hammers vibrate at same frequency as the frequency of voltage they are powered by. Lack of contacts makes them more reliable than DC bells.

Some electric bells have two cups which generate different tones. When the hammer goes in one direction, it hits one cup, when it moves back, it hits another cup. The sound of such two-tone electric bells is more pleasant.

14.EARTHQUAKE

An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are recorded with a seismometer, also known as a seismograph. The moment magnitude of an earthquake is conventionally reported, or the related and mostly obsolete Richter magnitude, with magnitude 3 or lower earthquakes being mostly imperceptible and magnitude 7 causing serious damage over large areas. Intensity of shaking is measured on the modified Mercalli scale.

Most naturally occurring earthquakes are related to the tectonic nature of the Earth. Such earthquakes are called tectonic earthquakes. The Earth's lithosphere is a patchwork of plates in slow but constant motion caused by the release to space of the heat in the Earth's mantle and core. The heat causes the rock in the Earth to flow on geological timescales, so that the plates move slowly but surely. Plate boundaries lock as the plates move past each other, creating frictional stress. When the frictional stress exceeds a critical value, called local strength, a sudden failure occurs. The boundary of tectonic plates along which failure occurs is called the fault plane. When the failure

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at the fault plane results in a violent displacement of the Earth's crust, energy is released as a combination of radiated elastic strain seismic waves, frictional heating of the fault surface, and cracking of the rock, thus causing an earthquake. This process of gradual build-up of strain and stress punctuated by occasional sudden earthquake failure is referred to as the Elastic-rebound theory. It is estimated that only 10 percent or less of an earthquake's total energy is radiated as seismic energy. Most of the earthquake's energy is used to power the earthquake fracture growth or is converted into heat generated by friction. Therefore, earthquakes lower the Earth's available elastic potential energy and raise its temperature, though these changes are negligible compared to the conductive and convective flow of heat out from the Earth's deep interior.[1]

15.CFL Lamp

A fluorescent lamp is a gas-discharge lamp that uses electricity to excite mercury vapor in argon or neon gas, resulting in a plasma that produces short-wave ultraviolet light. This light then causes a phosphor to fluoresce, producing visible light.

The main principle of fluorescent tube operation is based around inelastic scattering of electrons. An incident electron (emitted from the coating on the coils of wire forming the cathode electrode) collides with an atom in the gas (such as mercury, argon or krypton) used as the ultraviolet emitter. This causes an electron in the atom to temporarily jump up to a higher energy level to absorb some, or all, of the kinetic energy delivered by the colliding electron. This is why the collision is called 'inelastic' as some of the energy is absorbed. 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. The photons that are released from the chosen gas mixtures tend to have a wavelength in the ultraviolet part of the spectrum. This is not visible to the human eye, so must be converted into visible light. This is done by making use of fluorescence. This fluorescent conversion occurs in the phosphor coating on the inner surface of the fluorescent tube, where the ultraviolet photons are absorbed by electrons in the phosphor's atoms, 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 specially 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 to heat up the phosphor coating

16. Internet

The Internet is a worldwide, publicly accessible series of interconnected computer networks that transmit data by packet switching using the standard Internet Protocol (IP). It is a "network of networks" that consists of millions of smaller domestic, academic, business, and government networks, which together carry various information and services, such as electronic mail, online chat, file transfer, and the interlinked Web pages and other documents of the World Wide Web.

Today internet

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Aside from the complex physical connections that make up its infrastructure, the Internet is facilitated by bi- or multi-lateral commercial contracts (e.g., peering agreements), and by technical specifications or protocols that describe how to exchange data over the network. Indeed, the Internet is essentially defined by its interconnections and routing policies

As of June 10, 2007, 1.133 billion people use the Internet according to Internet World Stats. Writing in the Harvard International Review, philosopher N.J.Slabbert, a writer on policy issues for the Washington DC-based Urban Land Institute, has asserted that the Internet is fast becoming a basic feature of global civilization, so that what has traditionally been called "civil society" is now becoming identical with information technology society as defined by Internet use. [4]

Internet protocols

In this context, there are three layers of protocols:

At the lower level (OSI layer 3) is IP (Internet Protocol), which defines the datagrams or packets that carry blocks of data from one node to another. The vast majority of today's Internet uses version four of the IP protocol (i.e. IPv4), and although IPv6 is standardized, it exists only as "islands" of connectivity, and there are many ISPs without any IPv6 connectivity. [1]. ICMP (Internet Control Message Protocol) also exists at this level. ICMP is connectionless; it is used for control, signaling, and error reporting purposes.

TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) exist at the next layer up (OSI layer 4); these are the protocols by which data is transmitted. TCP makes a virtual 'connection', which gives some level of guarantee of reliability. UDP is a best-effort, connectionless transport, in which data packets that are lost in transit will not be re-sent.

The application protocols sit on top of TCP and UDP and occupy layers 5, 6, and 7 of the OSI model. These define the specific messages and data formats sent and understood by the applications running at each end of the communication. Examples of these protocols are HTTP, FTP, and SMTP.

Common uses of the Internet E-mail

The concept of sending electronic text messages between parties in a way analogous to mailing letters or memos predates the creation of the Internet. Even today it can be important to distinguish between Internet and internal e-mail systems. Internet e-mail may travel and be stored unencrypted on many other networks and machines out of both the sender's and the recipient's control. During this time it is quite possible for the content to be read and even tampered with by third parties, if anyone considers it important enough. Purely internal or intranet mail systems, where the information

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never leaves the corporate or organization's network, are much more secure, although in any organization there will be IT and other personnel whose job may involve monitoring, and occasionally accessing, the email of other employees not addressed to them.

Remote access

The Internet allows computer users to connect to other computers and information stores easily, wherever they may be across the world. They may do this with or without the use of security, authentication and encryption technologies, depending on the requirements.

File sharing

A computer file can be e-mailed to customers, colleagues and friends as an attachment. It can be uploaded to a Web site or FTP server for easy download by others. It can be put into a "shared location" or onto a file server for instant use by colleagues. The load of bulk downloads to many users can be eased by the use of "mirror" servers or peer-to-peer networks. In any of these cases, access to the file may be controlled by user authentication; the transit of the file over the Internet may be obscured by encryption and money may change hands before or after access to the file is given. The price can be paid by the remote charging of funds from, for example a credit card whose details are also passedhopefully fully encryptedacross the Internet. The origin and authenticity of the file received may be checked by digital signatures or by MD5 or other message digests.

Streaming media

Many existing radio and television broadcasters provide Internet 'feeds' of their live audio and video streams (for example, the BBC and Rush Limbaugh). They may also allow time-shift viewing or listening such as Preview, Classic Clips and Listen Again features. These providers have been joined by a range of pure Internet 'broadcasters' who never had on-air licenses. This means that an Internet-connected device, such as a computer or something more specific, can be used to access on-line media in much the same way as was previously possible only with a television or radio receiver. The range of material is much wider, from pornography to highly specialized technical Web-casts. Podcasting is a variation on this theme, whereusually audiomaterial is first downloaded in full and then may be played back on a computer or shifted to a digital audio player to be listened to on the move. These techniques using simple equipment allow anybody, with little censorship or licensing control, to broadcast audio-visual material on a worldwide basis.

Webcams can be seen as an even lower-budget extension of this phenomenon. While some webcams can give full frame rate video, the picture is usually either small or updates slowly. Internet users can watch animals around an African waterhole, ships in the Panama Canal, the traffic at a local roundabout or their own premises, live and in real time. Video chat rooms, video conferencing, and remote controllable webcams are also popular. Many uses can be found for personal webcams in and around the home, with and without two-way sound.

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Marketing The Internet has also become a large market for companies; some of the biggest companies today have grown by taking advantage of the efficient nature of low-cost advertising and commerce through the Internet; also known as e-commerce. It is the fastest way to spread information to a vast amount of people simultaneously. The Internet has also subsequently revolutionized shoppingfor example; a person can order a CD online and receive it in the mail within a couple of days, or download it directly in some cases. The Internet has also greatly facilitated personalized marketing which allows a company to market a product to a specific person or a specific group of people more so than any other advertising medium.

17. Solar cooker

Solar cookers are devices that heat food using only solar energy.Since they use no fuel and they cost nothing to run, humanitarian organizations are promoting their use worldwide to help slow deforestation and desertification caused by the need for firewood used to cook. Solar cookers are also sometimes used in outdoors cooking, especially in situations where minimal fuel consumption or fire risk are considered highly important.

Types of Solar Cookers There are many different types of Solar cookers. All solar cookers are based on a small pool of ideas to heat food with the sun's heat and light. The basic principles of solar cookers are:

Concentrating Sunlight: Some device, usually a mirror, is used to concentrate light and heat from the sun into a small cooking area, making the energy more concentrated and therefore more potent.

Converting Light to Heat: Any black on the inside of a solar cooker, as well as certain materials for pots, will improve the effectiveness of turning light into heat. A black pan will absorb almost all of the sun's light and turn it into heat, substantially improving the effectiveness of the cooker. Also, the better a pan conducts heat, the faster the oven will work.

Trapping Heat: Isolating the air inside the cooker from the air outside the cooker makes an important difference. Using a clear solid, like a plastic bag or a glass cover, will allow light to enter, but once the light is absorbed and converted to heat, a plastic bag or glass cover will trap the light inside using the Greenhouse Effect. This makes it possible to reach similar temperatures on cold and windy days as on hot days.

Alone, each of these strategies for heating something with the sun is fairly ineffective, but most solar cookers use two or all three of these strategies in combination to get temperatures sufficient for cooking.

Apart from the obvious need for sunlight and the need to aim the solar oven before use, using a solar oven is not substantially different from a conventional oven. However, one disadvantage of solar cooking is that it provides the hottest food during

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the hottest part of the day, when people are less inclined to eat a hot meal. However, a thick pan that conducts heat slowly (such as Cast Iron) will lose heat at a slower rate, and that combined with the insulation of the oven can be used to keep food warm well into the evening.

Solar Box Cookers

A solar box cooker is an insulated box with a transparent top and a reflective lid. The top can usually be removed to allow dark pots containing food to be placed inside. The box usually has one or more reflectors with aluminum foil or other reflective material to bounce extra light into the interior of the box. Cooking containers and the inside bottom of the cooker should be dark-colored or black. The inside walls should be reflective to reduce radiative heat loss and bounce the light towards the pots and the dark bottom, which is in contact with the pots.

The inside insulator for the solar box cooker has to be able to withstand temperatures up to 150 C (302 F) without melting or off-gassing. Crumpled newspapers, wool, rags, dry grass, sheets of cardboard, etc. can be used to insulate the walls of the cooker, but since most of the heat escapes through the top glass or plastic, very little insulation in the walls is necessary. The transparent top is either glass, which is durable but hard to work with, or an oven cooking bag, which is lighter, cheaper, and easier to work with, but less durable. If dark pots and/or bottom trays cannot be located, these can be darkened either with flat-black spray paint (one that is non-toxic when dry) or black tempera paint.

The solar box cooker typically reaches a temperature of 150 C (302 F); not as hot as a standard oven, but still hot enough to cook food over a somewhat longer period of time. It should be remembered that food containing moisture cannot get much hotter than 100 C (212 F) in any case, so it is not necessary to cook at the high temperatures indicated in standard cookbooks. Because the food does not reach too high a temperature, it can be safely left in the cooker all day without burning. It is best to start cooking before noon, though. Depending on the latitude and weather, food can be cooked either early or later in the day. The cooker can be used to warm food and drinks and can also be used to pasteurize water or milk.

Solar box cookers can be made of locally available materials or be manufactured in a factory for sale. They range from small cardboard devices, suitable for cooking a single meal when the sun is shining, to wood and glass boxes built into the sunny side of a house. Although invented by Horace de Saussure, a Swiss naturalist, as early as 1767, solar box cookers have only gained popularity since the 1970s. These surprisingly simple and useful appliances are seen in growing numbers in almost every country of the world. An index of detailed wiki pages for each country can be found here.

Environmental advantages Solar ovens are just one part of the alternative energy picture, but one that is accessible to a great majority of people. A reliable solar oven can be built from everyday materials in just a few hours or purchased ready made.

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Solar ovens can be used to prepare anything that can be made in a conventional oven or stovefrom baked bread to steamed vegetables to roasted meat. Solar ovens allow you to do it all, without contributing to global warming or heating up the kitchen and placing additional demands on cooling systems. Nearly 75 percent of US households prepare at least one hot meal per day; one-third prepare two or more. Some of those meals could be made in an environmentally responsible way, using a solar oven.

The World Health Organization reports that cooking with fuel wood is the equivalent of smoking two packs of cigarettes a day. Inhalation of smoke from cooking fires causes respiratory diseases and death. One of the solutions advocated to address this problem is solar cooking which makes no smoke at all. It just uses free and abundant solar energy.

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Refrigeration cycleModern ironing equipmentManual home ironsAutomatic ironing robots and major home appliancesInternet protocols

Common uses of the InternetE-mailRemote accessStreaming media

Marketing17. Solar cookerTypes of Solar CookersSolar Box Cookers

Environmental advantages