Semiconductors were being studied in laboratories as early as the 1830's. The materials were usually poor conductors if heated and often carried photoelectric properties. (Electrical production by shining light on the material.) Soon, this property of changing conductivity would become of vital importance to the world of electronics and communications. (Micron) Common semiconductors include silicon, zinc and germanium; however, silicon is by far the most widely implemented due to its abundance. Also, its reasonable speed, simple processing, and useful temperature range make it a good choice among other semiconductors. (Wikipedia - Semiconductor Device) This element has been used to make cast iron, bricks, and pottery, and glass, but it found a new technological purpose. Silicon is extracted from sand and altered using small amounts of impurities (more on that later) so the electrical current across the silicon can be regulated depending on the polarity of the electrical charge applied to it. Before semiconductors (1600's to 1800's), the vacuum tube dominated electronics. Radios, and even computers used vacuum tubes in their circuits. However, semiconductors in the form of transistors, replaced vacuum tubes because they …show more content…
If a positive charge is placed on the p-type side, the holes are pushed toward the junction. At the same time, the electrons in the n-type materials are attracted toward the junction. Since there is an abundance of carriers at the junction, current can flow through the junction from a power supply. However, if the charges placed on the semiconductor are reversed, the holes and the electrons are pulled away from the junction, leaving a relatively non-conducting silicon region which stops current flow. These can get more complicated by creating a third region, such as p-n-p or n-p-n. This 3-way configuration is called a transistor.
Electricity is an interesting subject. There is so much you can learn from it, like how our lights turn on or how we make cell phones. This is all a mystery until we finally get a little bit of information in our brains. I've just read two articles, "Energy Story" and "Conducting solutions". I also watched a video called Hands-on Science with Squishy circuits. I learned so much valuable information from these resources.
The first term that I noted during the movie was Conductive Polymers. Conductive polymers are almost always organic meaning a large class of chemical compounds whose molecules contain carbon. These polymers have extended delocalized bonds which are bonds found in a molecule that do not belong to a single atom or covalent bond. They are conjugated systems of double bonds and in a aromatic systems. The conjugated systems are atoms covalently bonded with alternating single and double bonds. When the electrons are removed or added into the valence bands the electrical conductivity increases. The conductive polymer has a low conductivity until the electron is removed from the valence band called (p-doping) or (n-doping) until it becomes more conductive. The movement of the charges is what is responsible for electrical conductivity. These polymers are plastic which are organic polymers and with mechanical properties such as flexibility and elasticity.
[IMAGE] Most reactive Potassium Sodium Lithium Calcium Magnesium Aluminium Zinc Iron Tin Lead Copper ------ Silver Gold Potassium Least reactive Electrical flow through metals work like this: the current in the metal is carried by electrons and will only flow if there charges which can move freely.
Central Idea: Nuclear energy only contributes a small amount to the world’s electricity yet it has hazards and dangers that far out-way its benefits. There are many other alternative power producing sources that can produce energy more efficiently and more safely than nuclear power plants can.
Conduction, convection and radiation are the three methods through which heat can be transferred from one place to another. The (www.hyperphysics.com) first method is the conduction through which heat can be transferred from one object to another object. This process is defined as the heat is transmitted from one to another by the interaction of the atoms and the molecules. The atoms and the molecules of the body are physically attached to each other and one part of the body is at higher temperature to the other part or the body, the heat begins to transfer. A simple experiment through which conduction can be understood easily is as follows. First of all, take a metallic rod of any length. Hold the rod in the hand or at any stand made up of the insulator so that the heat does not transfer to the stand. Heat up the one end of the rod with the help of the spirit lamp. After sometime, touch the other end of the end, the other end of the becomes heated too and the temperature of the other end of the rod has also increased. Although only one end of the rod is heated with the spirit lamp, but the other end of the rod has also been heated. This is represents that the heat has been transferred from one end of the rod to the other end of the rod without heating it from the other end. So, the transformation of the heat is taking place. This process is called the conduction. Conduction is a process which is lead by the free electrons. As the conduction happens occurs only in the metallic materials, the reason for it is that the metals has the free electrons and they can move freely from one part of the body to another part of the body. These electrons are not bounded by the nucleus so, they can move easily. And when the temperature of the ...
Thomas Edison, famed for inventing the light bulb and phonograph, embraced the standard method of direct-current, or DC, power distribution. Produced by batteries and dynamos, DC describes the unidirectional flow of an electrical charge. But George Westinghouse, the electrical engineer who built a fortune by making improvements to America’s railroad system, threw his weight behind the development of a power network based on alternating current, or AC, a more efficient transmission method whose magnitude changes cyclically. Nikola Tesla, one of the most eccentric and prolific electrical engineers in history also was in favor of AC. Tesla, whose work formed the basis of AC power, is one of the most admired pioneers in electrical engineering. In the 20th century, electrical engineering, like many other technologies, has expanded leaps and bounds. By 1900, the radio was already in common use, and developments over the next few decades made it even more useful. Guglielmo Marconi, the inventor of the telegraph, made radio useful worldwide, developing the first transatlantic radio transmissions. During and after World War II, radio became more prevalent in communications and guidance. The development of the integrated circuit in 1958 led to the advent of electronic engineering, after which came the personal computer,
In the mid?1950's, the transistor was introduced, creating a more reliable computer. Computers were used primarily for scientific and engineering calculations and were programmed mainly in FORTRAN and assembly language.
To understand how this electricity works we must start with the basics. The atom is the smallest unit of matter, consisting of protons, neutrons, and electrons. Protons have a positive charge, neutrons have no charge, and electrons have a negative charge. Electric charges that are the same repel each other and charges that are different attract each other. Electric charges can exist alone, unlike magnetic poles.
It involves collisions between the free electrons, the fixed. particles of the metal, other free electrons and impurities. These collisions convert some of the energy that the free electrons are. carrying heat, which means that electrical energy is lost. Apparatus: I will be using an Ammeter.
What is electricity? The term electricity means the force that makes electronics move from place to another. This is similar to the meaning of the engine as the force that moves a car or any mechanical machine. However, here it is explained as the effect not the physical movement. Throughout the ages, scientists have realized that electricity’s behavior can be predictable pattern when subjected to given conditions (Naiah & Kamakshaiah, 1995). What Electrical engineering? Electrical engineering is a field that deals with the applications the technology of electricity, such as generating, distributing electrical energy, and programing electrical systems.
The invisible bits of negatively charged matter that move between objects are called electrons. The words electron, electricity, and electronics all come from the Greek word for amber – elektron. The transfer of electrons explains the electric force that attracts the balloon to the wool. Rubbing the neutral balloon with the wool cloth allows some electrons to leave the wool and stick to the balloon.
Again, it is the most common means of energy transfer and by understanding exactly what conduction means, we can identify it in some of the simple things we do. For instance, think of a pot placed on the stove, on a hot burner. The burner and the bottom of the pot are obviously touching, therefore the pot begins to heat up and get hot as well. As physical contact is the key element in heat transfer through conduction, we can see how important a role it plays in this situation. Now, say that your food is done, you turn the burner off and grab the handle of the pot, only to find that it is extremely hot as well. Again, we can thank conduction for this- as the heat was transferred through the bottom of the pot to the handle. Another example of conduction can be seen through ironing. We plug in and heat up the iron prior to placing it on the clothing in which we wish to smooth out. Once the iron has heated up, we place it on top of the article of clothing and it then heats up the clothing as well. Again, physical contact between the iron and the shirt show us that conduction plays the role of heat transfer in this scenario too. For a final example of heat transfer through conduction, let’s imagine a child, playing outside in the snow on a rather cold day. Once outside for a bit, he is freezing and decides to come inside. He takes off his snow gear, cuddles up to his father and begins to warm up
The history of engineering goes back into the 19th century when Alexander Volta (1745-1827) made a remarkable discover regarding the nature of electricity (Cosgrove 749). He discovered that electrical current could be controlled and could flow from one point to another. By the time the mid-19th century came about the rules for electricity were being established. During this time electromagnetic induction was discovered by Michael Faraday who lived from 1791 to 1867 (749). Also during this time Samuel Morris invented the telegraph in 1837 which relies on the principles of electromagnetic induction (749). Alexander Graham Bell, who lived from 1847 to 1922, created the telephone which also uses electricity in order to operate (749). Through the success of the telephone, Bell Telephone Company was established. In 1878, the light bulb was finally invented by Thomas Edison who lived from 1847 to 1931 (749). Off the principles of Faraday’s electric motor from 1821, Nicholas Tesla invented a more efficient and powerful electric motor in 1888 (749). To make these inventions be more significant, effort was expended to make better motors and transformers and to enhance the power needed to make them function. Through these inventions during the middle 19th century, it led to the capability of lighting homes and cities through the use of electricity, and it also led to the creation of the telephone communication system (750).
As an engineering student, design, develop and test electrical equipments is the major purpose of all time. In other words, electrical engineer is concerned with using electricity to transmit electric power. In electrical engineering, there are extensive subfields such as power engineering, control system and signal processing. It is also worth to point out the difference between electrical engineering and electronic engineering. According to the research, electronic engineering is a major that deal with the electronic system such as computers and radar, to be more specific, electronic engineers are concerned with using electricity to process information.
Figure 1 illustrates the design of the batteries discovered in ancient Persia. Fast forwarding to the 17th century, it was “in the year 1600, English Physician William Gilbert used the Latin word “electricus” to describe the force that certain substances exert when rubbed against each other” (Atkinson, 2014). Though Benjamin Franklin is largely accredited with the discovery of electricity, it was “Italian physicist Alessandro Volta [whom] discovered that particular chemical reactions could produce electricity” (Atkinson, 2014). In “1800, he constructed an early electric battery that produced a steady current” (Atinkson, 2014). To clarify, current is defined as the “rate at which charge flows through its surface” (Serway and Vuille, 2011). Volta ‘s battery was only the beginning. Michael Faraday made electricity more accessible when he “created the electric dynamo (a crude power generator)” (Atinkson, 2014). This invention “solved the problem of generating electric current in an ongoing and practical way” (Atinkson, 2014). Faraday’s solution helped Thomas Edison invent his famous light bulb because it was the “first practical bulb that would light for hours on end” (Atinkson, 2014). Edison is