Sadaf Media

Do You Know About Top Five Search Engine Name's ??

Top five search engine's are-

1.Google-

Google is one of the five most popular website in the world. Google is a web search engine that lets you find other sites on the web based on keyword searches. Google also provides specialized searches through blogs, catalogs, videos, news items and more.

Google provides Internet services that let you create blogs, send email, and publish webpages. Google has social networking tools, organization tools, and chat tools, services for mobile devices, and even Google branded merchandise.

According to the latest comscore report (October 2012) 69.5% of searches were powered by Google and 25% by Bing. Google is also dominating the mobile/tablet search engine market share with 89%!

3.Yahoo-

The search engine that helps you find exactly what you're looking for. Find the most relevant information, video, images, Web.Yahoo Search is a web search engine owned by Yahoo! , and was, as of January 2014, the second largest search directory on the web.

Since October 2011 Yahoo search is powered by Bing. Yahoo is still the most popular email provider and according to reports holds the third place in search.

3.Bing-

Bing is Microsoft’s attempt to challenge Google in the area of search but despite their efforts they still did not manage to convince users that their search engine can produce better results than Google.

4.Ask.com-

Formerly known as Ask Jeeves, Ask.com receives approximately 3% of the search share. ASK is based on a question/answer format where most questions are answered by other users or are in the form of polls. It also has the general search functionality but the results returned lack quality compared to Google or even Bing and Yahoo.

5.AOL.com-

According to netmarketshare the old time famous AOL is still in the top 10 search engines with a market share that is close to 0.6%. The AOL network includes many popular web sites like engadget.com, techchrunch.com and the huffingtonpost.com.

''Michael Faraday ''Discovered First

Semiconductor Effect-

Michael Faraday describes the "extraordinary case" of his discovery of electrical conduction increasing with temperature in silver sulfide crystals. This is the opposite to that observed in copper and other metals.

Michael Faraday

Faraday's experimental work in chemistry, which included the discovery of benzene, also led him to the first documented observation of a material that we now call a semiconductor. While investigating the effect of temperature on "sulphurette of silver" (silver sulfide) in 1833 he found that electrical conductivity increased with increasing temperature. This effect, typical of semiconductors, is the opposite of that measured in metals such as copper, where conductivity decreases as temperature is increased.

We now understand that raising the temperature of most semiconductors increases the density of charge carriers inside them and hence their conductivity. This effect is used to make thermistors - special resistors that exhibit a decrease in electrical resistance (or an increase in conductivity) with an increase in temperature.

What is Semiconductor and How it can

work??

A semiconductor is a substance, usually a solid chemical element or compound, that can conduct electricity under some conditions but not others, making it a good medium for the control of electrical current. Its conductance varies depending on the current or voltage applied to a control electrode, or on the intensity of irradiation by infrared IR, visible light, ultraviolet (UV), or X rays.

8 inch silicon wafer chip .

A semiconductor material has an electrical conductivity value between a conductor, such as copper, and an insulator, such as glass. Semiconductors are the foundation of modern electronics. The modern understanding of the properties of a semiconductor relies on quantum physics to explain the movement of electrons and holes in a crystal lattice. An increased knowledge of semiconductor materials and fabrication processes has made possible continuing increases in the complexity and speed of microprocessor and memory devices.

Semiconductor chip

There are Two types of Semiconductor-

1. Intrinsic semiconductor.

2. Extrinsic semiconductor.

Intrinsic semiconductor-

An intrinsic semiconductor, also called an undoped semiconductor or i-type semiconductor, is a pure semiconductor without any significant dopant species present. The number of charge carrier is therefore determined by the properties of the material itself instead of the amount of impurities. In intrinsic semiconductors the number of excited electrons and the number of holes are equal: n = p.

A silicon crystal is different from an insulator because at any temperature above absolute zero, there is a finite probability that an electron in the lattice will be knocked loose from its position, leaving behind an electron deficiency called a "hole". If a voltage is applied, then both the electron and the hole can contribute to a small current flow.

The conductivity of a semiconductor can be modeled in terms of the band theory of solids. The band model of a semiconductor suggests that at ordinary temperatures there is a finite possibility that electrons can reach the conduction band and contribute to electrical conduction.

Extrinsic semiconductor-They are of two types'n-type semiconductor and p-type semiconductor.

current conduction in a semiconductor occurs through the movement of free electrons and "holes", collectively known as charge carriers. Adding impurity atoms to a semiconducting material, known as ''doping'', greatly increases the number of charge carriers within it. When a doped semiconductor contains mostly free holes it is called "p-type", and when it contains mostly free electrons it is known as "n-type". The semiconductor materials used in electronic devices are doped under precise conditions to control the location and concentration of p- and n-type dopants. A single semiconductor crystal can have many p- and n-type regions; the p-n junction between these regions are responsible for the useful electronic behaviour.

p-type semiconductor.

n-type semiconductor.

Band gap in p-type and n-type semiconductor-

Basic electronic device's-

Diode-

Diode is a marvelous device that passes current only in one direction. Its not necessary that a diode is made of semiconductor, it could be made using vacuum tube valve technology or using electromagnetic switch or using a crystal. We over here concentrate about Semiconductor Diode Alone.

symbol of diode.

Diodes can be used for various applications like Voltage Rectification & Regulation, Clipping & Clamping of voltages, making digital logic circuits, modulation, photo-voltaics and so on. Light Emitting Diodes (LED's) are used for light production in visible and invisible region of Electromagnetic spectrum. Many nations have switched their traffic light to LED's so that they have higher operational efficiency. PIN diodes are used for electricity production from light, they constitute much of Solar Cells. Apart from this diodes have many other application which my limited knowledge has failed to take notice.

A simple diode.

There are different types of diode such as p-n junction diode, pin diode , photo diode, varactor diode and led.

1. p-n junction diode- A p–n junction is a boundary or interface between two types of semiconductor material, p-type and n-type, inside a single crystal semiconductor. It is created by doping, for example by ion implantation, diffusion of dopants, or by (growing a layer of crystal doped with one type of dopant on top of a layer of crystal doped with another type of dopant). If two separate pieces of material were used, this would introduce a grain boundary between the semiconductors that would severely inhibit its utility by scattering the electrons and holes.

symbol of p-n junction diode.

2.Photodiode-

A light sensor (photodetector) that allows current to flow in one direction from one side to the other when it absorbsphotons (light). The more light, the more current. Used to detect light pulses in optical fibers and other light-sensitive applications, aphotodiode is the opposite of a light emitting diode . Photodiodes detect light and let electricity flow; LEDs receive electricity andemit light.

symbol of photodiode.

A semiconductor diode in which the reverse current varies with illumination; examples include the alloy-junction photocell and the grown-junction photocell. Also known as photoconductor diode.

Photodiode.

3. Pin diode-

The PIN diode, p-i-n diode is essentially a refinement of the ordinary PN junction diode. Its development arose from the original PN diode development activities and applications for the new diode were soon found.

Symbol of pin diode.

The PIN diode differs from the basic PN junction diode in that the PIN diode includes a layer of intrinsic material between the P and N layers. As a result of the intrinsic layer, PIN diodes have a high breakdown voltage and they also exhibit a low level of junction capacitance. In addition to this the larger deletion region of the PIN diode is ideal for applications as a photodiode.

Pin diode.

3.LED-

A light-emitting diode (LED) is a two-lead semiconductor light source It is a basic pn junction diode, which emits light when activated.When a suitable voltage is applied to the leads, electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence and the color of the light (corresponding to the energy of the photon) is determined by the energy band gap of the semiconductor

Symbol of LED.

LED.

4. Zener diode-

A Zener diode is a diode which allows current to flow in the forward direction in the same manner as an ideal diode, but also permits it to flow in the reverse direction when the voltage is above a certain value known as the breakdown voltage, "Zener knee voltage", "Zener voltage", "avalanche point", or "peak inverse voltage".the reverse breakdown is due to electron quantum tunnelling under high electric field strength—the zener effect. However, many diodes described as "Zener" diodes rely instead on avalanche breakdown as the mechanism. Both types are used with the Zener effect predominating under 5.6 V and avalanche breakdown above. Common applications include providing a reference voltage for voltage regilator or to protect other semiconductor devices from momentary voltage pulses.

Zener diode.

Resistor-

A resistor is a passive two terminal electrical component that implements electrical resistance as a circuit element. Resistors act to reduce current flow, and, at the same time, act to lower voltage levels within circuits. In electronic circuits resistors are used to limit current flow, to adjust signal levels, bias active elements, terminate transmission line among other uses. High-power resistors that can dissipate many watts of electrical power as heat may be used as part of motor controls, in power distribution systems, or as test loads for generators. Resistors can have fixed resistances that only change slightly with temperature, time or operating voltage.

Symbol of resistor.

Resistor.

Capacitor-

In a way, a capacitor is a little like a battery. Although they work in completely different ways, capacitors and batteries both store electrical energy. If you have read How battery work, then you know that a battery has two terminals. Inside the battery, chemical reactions produce electron on one terminal and absorb electrons on the other terminal. A capacitor is much simpler than a battery, as it can't produce new electrons -- it only stores them.

Electrolytic capacitor.

Unpolarized capacitor.

Inside the capacitor, the terminals connect to two metal platesseparated by a non-conducting substance, or dielectric. You can easily make a capacitor from two pieces of aluminum foil and a piece of paper. It won't be a particularly good capacitor in terms of its storage capacity, but it will work.

Inductor-

An inductor is a passive electronic component that storesenergy in the form of a magnetic field. In its simplest form, an inductor consistsof a wire loop or coil. The inductance is directly proportional to the number ofturns in the coil. Inductance also depends on the radius of the coil and on the type of material around which the coil is wound.

Inductor.

For a given coil radius and number of turns, air coresresult in the least inductance. Materials such as wood, glass, and plastic - known as dielectric materials - are essentially the same as air for the purposes of inductor winding. Ferromagnetic substances such as iron, laminated iron, and powdered iron increase the inductance obtainable with a coil having a given number of turns. In some cases, this increase is on the order of thousands of times. The shape of the core is also significant. Toroidal (donut-shaped) cores provide more inductance, for a given core material andnumber of turns, than solenoidal (rod-shaped) cores.

Filter-

Electronic filters are analog circuit which perform signal processing functions, specifically to remove unwanted frequency components from the signal, to enhance wanted ones, or both. Electronic filter can be:

passive or active.
analog or digital.
high pass, low pass, band pass, band stop, (band-rejection; notch), or all pass.
discrete time (sampled) or continuous time.
linear or non- linear.
infinite pulse response (IIR type) or finite pulse response(FIR type).
The most common types of electronic filters are linear filter, regardless of other aspects of their design. See the article on linear filters for details on their design and analysis.

Linear filter.

Ceramic filter.

Crystal filter.

Amplifier-

An electronic amplifier, or (informally) amp is an electronic device that increases the power of a signal.

It does this by taking energy from a power supply and controlling the output to match the input signal shape but with a larger amplitude. In this sense, an amplifier modulates the output of the power supply to make the output signal stronger than the input signal.

Simple amplifier symbol.

The four basic types of electronic amplifiers are voltage amplifiers, current amplifiers, transconductance amplifiers. A further distinction is whether the output is a linear or non linear representation of the input. Amplifiers can also be categorized by their physical placement in the signal chain.

Amplifier Icon.

Transistor-

A transistor is an electronic component that can be used as an amplifier,, or as a switch. They are found in most electronic devices..

A transistor has three connectors or terminals. In the older bipolar transistor they are the collector, the emitter, and the base. The flow of charge goes in the collector, and out of the emitter, depending on the charge flowing to the base. In this way, it is possible for the base to switch on or off the flow through the transistor.

The transistor can be used for a variety of different things including amplifiers and digital switches for computer microprocessors.. Digital work mostly uses mosfet.. Some transistors are individually packaged, mainly so they can handle high power. Most are in IC's

There are two types of transistor-

1.NPN transistor.

2.PNP transistor.

NPN transistor-

By NPN we mean negative-positive-negative transistor. NPN transistors comprise a positive layer positioned amid 2 negative layers. Where, NPN is the most common type of Bipolar Junction Transistor (BJT) used in many circuits.

The diagram shown above of NPN transistor shows that transistor is employed as switch. A minute voltage or current at the bottom permits a superior voltage to run all the way through the other 2 legs from the collector to the emitter. The second diagram above of NPN transistor shows that when the switch is pushed a current is passed all the way through the resistor in the bottom of the transistor. The transistor then permits current to run from +9 voltages to the 0 volts, and the bulb of the lamp glows on.

The transistor needs to collect a voltage at its ‘bottom’ and until this occurs the lamp does not glow. The resistor is exists to shield the transistor as they may be injured quickly by extremely high voltage or current. Transistors are a vital constituent in a lot of circuits and are at times employed to intensify a signal.

PNP transistor-

The opposite of NPN transistor is the PNP transistor. Fundamentally, in this sort of transistor’s structure the 2 diodes are upturned with reference to the NPN sort providing a Positive-Negative-Positive pattern, with the à (arrow) which also describes the Emitter terminal this moment spotting inside in the transistor emblem.

All the polarization for a PNP transistor are upturned , the meaning of this is that it “drops” current into its bottom as opposite to the NPN transistor which “supplies” current all the way through its bottom. The major variation amid the 2 sorts of transistors is that holes are the more significant transporters for PNP transistors, while electrons are the significant transporters for NPN transistors.

PNP transistors bring into play a minute base current and a negative bottom voltage to direct a much superior emitter collector current. In simple terms, for PNP transistor, the Emitter is additional positive in consideration to the base and also in consideration to the collector.

The structure of a PNP transistor includes 2 P-type semi-conductor substances on both side of an N-type substance as revealed in the figure below.

Resource site: Electronics-Tutorials.ws