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Electric Circuits and Components
Published in Quamrul H. Mazumder, Introduction to Engineering, 2018
A conductor is a material that lets electrons flow through it very easily, while an insulator is made up of materials that oppose the flow of electrons through it. Metals are usually the best conductors because their valence electrons have weak bonds, and these electrons are free to move around the solid object. The structure of a metal can be best described as some positive ions located in a sea of free flowing electrons. This is why metals like copper are used to manufacture electric wires. On the other hand, insulators have no free electrons and thus no flow of electrons. Because most elements in the periodic table are metals and likely to be good conductors, the best insulator tends to be plastic. The insulating material of wires is made of plastic that ensures that the conductive metal inside is not exposed.
Effects of Harmonics
Published in J.C. Das, Harmonic Generation Effects Propagation and Control, 2018
where Ycs is due to conductor resistance resulting from skin effect and Ycp is due to proximity effect. The skin effect is an AC phenomenon, where the current density throughout the conductor cross section is not uniform and the current tends to flow more densely near the outer surface of the conductor than toward the center. This is because an AC flux results in induced EMFs which are greater at the center than at the circumference, so that potential difference tends to establish currents that oppose the main current at the center and assist it at the circumference. The result is that the current is forced to the outside, reducing the effective area of the conductor. The effect is utilized in high ampacity hollow conductors and tubular bus bars to save material costs. The skin effect is given by [16]
Renewable Energy Resources
Published in Julie Kerr, Introduction to Energy and Climate, 2017
By the seventeenth century, several electricity-related discoveries had been made, such as the invention of an early electrostatic generator, the differentiation between positive and negative currents, and the classification of materials as conductors or insulators. A conductor is a material through which an electrical current may pass; an insulator is a substance that does not readily conduct electricity. In the early 1600s English scientist, Thomas Browne, was conducting carefully planned “electricity” experiments. Then in 1752, Benjamin Franklin conducted his famous experiment with a kite, a key, and a storm. His experiment only proved that lightning and tiny electric sparks were the same thing. Following him, Italian physicist Alessandro Volta discovered that particular chemical reactions could produce electricity, and in 1800, he constructed the voltaic pile that produced a steady electric current, and so he was the first person to create a steady flow of electric charge. He was also the first to create a transmission of electricity by linking positively-charged and negatively-charged connectors and driving an electrical change or voltage through them.
Modeling and Fabrication Aspects of Cu- and Carbon Nanotube-Based Through-Silicon Vias
Published in IETE Journal of Research, 2021
Tanu Goyal, Manoj Kumar Majumder, Brajesh Kumar Kaushik
It is noticed that the resistance of TSV increases with frequency due to skin effect. Skin effect arises when a high-frequency current flows close to the surface of conductor due to the formation of eddy currents. This results in the current penetration through the conductors when frequency is varied. When the frequency is high enough such that the skin depth is smaller than the radius of the circular via-holes, the current starts to distribute unevenly and becomes crowded at the surface of the conductor. Hence, the resistance and inductance effectively increase and reduce with frequency [10]. where RTSV0 and LTSV0 are resistance and inductance of vias at 500 MHz frequency [10]. The lossy characteristics Rsub can be modeled as The current induced in the substrate rises as a result of high frequency that consequently reduces substrate resistance Rsub(f). The primary issue with this model was that it measured the resistance and inductance of large TSV structures but did not correlate them with the physical dimensions and material characteristics. Moreover, the model incorrectly ignores the substrate and oxide parasitic.
Induction assisted friction stir welding: a review
Published in Australian Journal of Mechanical Engineering, 2020
All metals show electric resistance while conducting electricity. The resistance to this flow of current causes losses in power that result in the formation of heat. Some metals, such as silver and copper, have very low resistance and, as a result they are very good conductors. Copper wires are used to carry electricity through power lines because of the low heat losses during transmission. Other metals, such as steel, have high resistance to an electric current, so that when an electric current is passed through steel, substantial heat is produced (Bhadeshia and DebRoy 2009). The steel heating coil on top of an electric stove is an example of heating due to the resistance to the flow of the household, 60 Hz electric current. In a similar manner, the heat produced in a part in an induction coil is due to the electrical current circulating in the part (Robson, Kamp, and Sullivan 2007).
Wearable electronic textiles
Published in Textile Progress, 2019
David Tyler, Jane Wood, Tasneem Sabir, Chloe McDonnell, Abu Sadat Muhammad Sayem, Nick Whittaker
Tang and Stylios [36] explain how developing garments with smart materials and wearable electronics can enable the sensing and responding actions. Key components to consider include flexible electrical and data conductivity, flexible sensors and actuators, wireless communication, and power supply. Conductive materials for example, fibre, yarns, fabrics (woven or knitted) and embroidery threads are essential elements for wearable technology. As the Oxford Dictionary [61] defines, ‘conductivity is the measure of the ease at which an electric charge or heat can pass through a material’. Therefore, the material is considered to be a conductor if it exhibits very little resistance to the flow of an electric current or thermal energy.