Electronics+Introduction

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= = = What are electronics? = Electronics are here to stay! I bet you can think of a lot of things that use electronics such as computers, mobile phones, DVD players and games consoles. Grocery stores, hospitals, airports and schools are full of electronic devices.

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What makes a device electronic? It is not just because it uses electricity!!! It is only electronic if certain electronic components are used to control the movement of electricity through electronic circuits. Electronics is the study of how small electric currents are controlled to make all kinds of electronic and electrical equipment work. Understanding electronics and how electronic devices work may seem daunting but by breaking electronic devices down into simple system or block diagrams and considering the **Input, Process, and Output** we can begin to understand how these devices work, and by taking a closer look at the components used, and their function can we begin to understand how the electronic world around us works.

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At this point you might be asking yourself what is electricity? Everything around us is made from very small particles called atoms and inside these atoms are even smaller particle called protons and electrons. The protons have a positive charge and the electrons a negative charge. Normally the number of protons and electrons in an atom is equal, i.e. the atom is //neutral//, however sometimes an object may steal electrons from another simply by brushing against it - the result is one of the objects becomes negatively charged whilst the other becomes positively charged. When two object come together, which are both charged alike then they repel each other, two objects the are oppositely charged - attract each other. Here is an example of using this effect to create a piece of art! media type="youtube" key="itLqZdchg1Y?fs=1" height="364" width="445" All substances contain **electrons**, they are part of the atoms which things are made of. For example //**you, the desk, this computer... EVERYTHING!**//



media type="youtube" key="EJeAuQ7pkpc?fs=1" height="385" width="480" When electrons move, they carry electrical energy from one place to another. A lightning bolt is one example of an electric current, although it does not last very long. Electric currents are also involved in powering all the electrical appliances that you use, from a washing machine to flashlights and from telephones to MP3 players. These electric currents last much longer. In certain substances, e.g. metal wire, electrons can be made to move easily by applying a power supply. Substances in which electrons move easily are called conductors. When we use electricity - we need to be able to measure the amount of current. Just like with weight and length we need a unit to help us describe how much current there is. We call the units for measuring electric current **Ampers** or **Amps**. and its symbol is** I **

= Lets take a closer look at electric current = You may wish to revise your chemistry at this site: **[|www.personal.psu.edu/.../chemistry1.htm]** or check out the video below media type="youtube" key="ZB7B_796mVs&hl=en&fs=1&color1=0xe1600f&color2=0xfebd01&border=1" height="349" width="425"

= Electron Flow = media type="youtube" key="77R4arwD8G8&hl=en&fs=1&color1=0xe1600f&color2=0xfebd01&border=1" height="349" width="425"
 * Valence electrons**
 * The outer shell of an atom is known as the valence shell.
 * Any electrons located in the outer shell of an atom are known as valence electrons.
 * The valence shell of an atom cannot hold more than eight electrons. It is the valence electrons that are primary concern in the study of electricity, because it is these that explain much of electrical theory.
 * A conductor for instance, is generally made from a material that contains one or two valence electrons.
 * Atoms with one or two valence electrons are unstable and can be made to give up these electrons with little effort.
 * Conductors are materials that permit electrons to flow through them easily.
 * When an atom has only one or two valence electrons, these electrons are loosely held by the atom and are easily given up for the current flow.
 * Silver, copper, gold, and aluminium all contain one valence electron and are excellent conductors of electricity.
 * Silver is the best natural conductor of electricity, followed by copper, gold, and aluminium.
 * Electrical current is the flow of electrons.
 * It is produced when an electron from one atom knocks electrons of another atom out of orbit.
 * When an atom contains only one valence electron, that electron is easily given up when struck by another electron.
 * The striking electron gives its energy to the electron being struck.
 * The striking electron settles into orbit around the atom, and the electron that was struck moves off to strike another electron.
 * Some energy is also lost when one electron strikes another. That is why a wire heats when current flows through it. If too much current flows through a wire, overheating will damage the wire and possibly become a fire hazard.
 * // This same effect in a pinball machine or a game of pool. If the moving cue ball strikes a stationary ball. The stationary ball then moves off with the most of the cue ball's energy, and the cue ball stops moving. The stationary ball did not move off with all the energy of the cue ball. It moved off with most of the energy of the cue ball. Some of the cue ball's energy was lost to heat when it struck the stationary ball. //
 * If an atom containing two valence electrons is struck by a moving electron, the energy of the striking electron will be divided between the two valence electrons.
 * If the valence electrons are knocked out of orbit, they will contain only half the energy of the striking electron.
 * // This effect can also be seen in a pinball machine or a game of pool. If a moving cue ball strikes two stationary balls at the same time, the energy of the cue ball is divided between the two stationary balls. Both stationary balls will move, but with only half of the cue ball. //

= Insulators = = Semiconductors =
 * Materials containing seven or eight valence electrons are known as insulators.
 * Insulators are materials that resist the flow of electricity.
 * When the valence shell of an atom is full, the electrons are held tightly and are not given up easily.
 * Some good examples of insulator materials are rubber, plastic, glass, and wood.
 * The energy of the moving electron is divided so many times that it has little effect on the atom.
 * Any atom that has seven or eight valence electrons is extremely stable and does not easily give up an electron.
 * Semiconductors are the materials that are neither good conductors nor good insulators.
 * They contain four valence electrons and are characterized by the fact that as they are heated, their resistance decreases.
 * Heat has the opposite effect on conductors, whose resistance increases with an increase of temperature.
 * Semiconductors have become extremely important in the electrical industry since the invention of the transistor in 1947.
 * All solid state devices such as diodes, transistors, and integrated circuits are made from combinations of semiconductors materials.
 * The two most common materials used in the production of electronic components are silicon and germanium.
 * Of the two, silicon is used more often because of its ability to withstand heat.
 * Before a pure semiconductor can be used to construct electronic device, it must be mixed or "doped" with an impurity.

If you want to know more try this website: = Resistance = Power Ohm's Law defines the relationships between (P) power, (E) voltage, (I) current, and (R) resistance. One ohm is the resistance value through which one volt will maintain a current of one ampere.
 * **http://elec-toolbox.com/theory.htm**

media type="custom" key="1839675" = Recap = ( I ) [|Current] is what flows on a wire or conductor like water flowing down a river. Current flows from negative to positive on the surface of a conductor. Current is measured in (A) amperes or amps.

( E ) [|Voltage] is the difference in electrical potential between two points in a circuit. It's the push or pressure behind current flow through a circuit, and is measured in (V) volts.

( R ) [|Resistance] determines how much current will flow through a component. [|Resistors] are used to control voltage and current levels. A very high resistance allows a small amount of current to flow. A very low resistance allows a large amount of current to flow. Resistance is measured in ohms.

( P ) [|Power] is the amount of current times the voltage level at a given point measured in wattage or watts.

And here is a link to A rough Guide to Electronics by Madlab:
 * **@http://www.madlab.org/electrnx/electrnx.html**

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