Fundamentals of Electronics

Fundamentals of Electronics - Fundamentals of Electronics...

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Fundamentals of Electronics Department of Electronic and Electrical Engineering University of Strathclyde Graham Hills Building 50 George Street Glasgow, G1 1QE Scotland, U.K.
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Dept. Electronic and Electrical Eng. 19.145 Lab TS00 Fundamentals of Electronics. 1 1 Introduction Electric currents flow along wires to transmit energy for domestic and industrial purposes. To understand many electrical phenomena, it is only necessary to learn a few simple rules of circuit analysis and these will be the underlying theme of this guide. This pre-course material establishes the basic definitions of electric charge, currents, voltage or electric potential energy. Secondly, it discusses the behaviour of currents in circuits and introduces some important circuit components. Ultimately, all of these processes can be understood in terms of the simple model of the atom dating from 1910, Figure 1. This is an example of a Carbon atom with six “orbiting” electrons each with a negative charge, - e, six protons each with a positive charge of + e and six neutrons with zero charge. Here e is the smallest currently measurable amount of charge, equal to 19 10 . 6 . 1 - coulombs. The net overall charge of the atom is zero. However, if any atom captures an extra electron its net charge becomes - e and is said to be negatively charged. Similarly, if a neutral atom loses an electron, its net charge becomes +e and is said to be positively charged. Figure 1 Atomic make-up of Carbon. Orbiting electrons each have a negative charge of e - , protons in the nucleus each have a positive charge e + . Neutrons have zero charge. -e +e
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Dept. Electronic and Electrical Eng. 19.145 Lab TS00 Fundamentals of Electronics. 2 2 Charge You are already familiar with one of the fundamental forces of nature, namely the gravitational force, which holds you securely to your seat. Now consider another force, the electrostatic force. This is the force responsible for binding atomic electrons to nuclei, the cores of atoms, and for holding atoms together to form microscopic molecules and macroscopic solids. Electrostatic force is not as apparent as gravitational force. But it is easy to perform electrostatic experiments. As a child you may have rubbed an inflated balloon on your jersey and then placed the balloon against the wall of a room and seen that the balloon sticks to it, Figure 2(a). Here, the electrostatic attraction between the balloon and wall is so large that it exceeds the gravitational force on the balloon. A similar experiment involves rubbing a piece of plastic, such as your ruler, on a woollen cloth Figure 2(b). The ruler can then lift small pieces of paper, rather as a magnet lifts a paper clip. Another example of the action of electrostatic forces can be seen when brushing your hair. If your hair is dry and you brush briskly, you will see that your hair is attracted to the brush. Under what circumstances do bodies like the balloon, the ruler and the hair
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This note was uploaded on 04/11/2010 for the course EE 110 taught by Professor Unknown during the Spring '10 term at École Normale Supérieure.

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Fundamentals of Electronics - Fundamentals of Electronics...

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