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barcode in vb.net 2005 Resistance and the ohm 27 in Software
Resistance and the ohm 27 Decoding QRCode In None Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications. QR Code JIS X 0510 Generation In None Using Barcode drawer for Software Control to generate, create QR Code JIS X 0510 image in Software applications. Table 21. Resistivity for copper wire, in terms of the size in American Wire Gauge (AWG). Decode Denso QR Bar Code In None Using Barcode decoder for Software Control to read, scan read, scan image in Software applications. Encode QR Code 2d Barcode In C#.NET Using Barcode generator for VS .NET Control to generate, create QR Code image in .NET framework applications. Wire size, AWG 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Resistivity, ohms/km 0.52 0.83 1.3 2.7 3.3 5.3 8.4 13 21 34 54 86 140 220 350 Denso QR Bar Code Printer In Visual Studio .NET Using Barcode maker for ASP.NET Control to generate, create QRCode image in ASP.NET applications. Print QR Code In VS .NET Using Barcode generation for .NET Control to generate, create QR Code ISO/IEC18004 image in .NET framework applications. deliver an unlimited number of charge carriers, there will be a current of 1A. If the resistance is doubled, the current is cut in half. If the resistance is cut in half, the current doubles. Therefore, the current flow, for a constant voltage, is inversely proportional to the resistance. Figure 23 is a graph that shows various currents, through various resistances, given a constant voltage of 1V across the whole resistance. QR Code JIS X 0510 Drawer In Visual Basic .NET Using Barcode maker for .NET framework Control to generate, create QR Code image in .NET framework applications. Encoding Bar Code In None Using Barcode printer for Software Control to generate, create bar code image in Software applications. 23 Current versus resistance through an electric device when the voltage is constant at 1 V.
Drawing EAN / UCC  13 In None Using Barcode creation for Software Control to generate, create EAN13 Supplement 5 image in Software applications. Data Matrix Encoder In None Using Barcode creation for Software Control to generate, create Data Matrix ECC200 image in Software applications. 28 Electrical units Resistance has another property in an electric circuit. If there is a current flowing through a resistive material, there will always be a potential difference across the resistive object. This is shown in Fig. 24. The larger the current through the resistor, the greater the EMF across the resistor. In general, this EMF is directly proportional to the current through the resistor. This behavior of resistors is extremely useful in the design of electronic circuits, as you will learn later in this book. Make Barcode In None Using Barcode generator for Software Control to generate, create bar code image in Software applications. Print Code 128 Code Set C In None Using Barcode encoder for Software Control to generate, create Code 128 Code Set C image in Software applications. 24 Whenever a resistance carries a current, there is a voltage across it.
DUN  14 Creator In None Using Barcode generator for Software Control to generate, create UPC Case Code image in Software applications. GS1  12 Generation In Java Using Barcode encoder for Java Control to generate, create UPC Code image in Java applications. Electrical circuits always have some resistance. There is no such thing as a perfect conductor. When some metals are chilled to extremely low temperatures, they lose practically all of their resistance, but they never become absolutely perfect, resistancefree conductors. This phenomenon, about which you might have heard, is called superconductivity. In recent years, special metals have been found that behave this way even at fairly moderate temperatures. Researchers are trying to concoct substances that will superconduct even at room temperature. Superconductivity is an active field in physics right now. Just as there is no such thing as a perfectly resistancefree substance, there isn t a truly infinite resistance, either. Even air conducts to some extent, although the effect is usually so small that it can be ignored. In some electronic applications, materials are selected on the basis of how nearly infinite their resistance is. These materials make good electric insulators, and good dielectrics for capacitors, devices that store electric charge. In electronics, the resistance of a component often varies, depending on the conditions under which it is operated. A transistor, for example, might have extremely high resistance some of the time, and very low resistance at other times. This high/low fluctuation can be made to take place thousands, millions or billions of times each second. In this way, oscillators, amplifiers and digital electronic devices function in radio receivers and transmitters, telephone networks, digital computers and satellite links (to name just a few applications). Code 39 Extended Drawer In ObjectiveC Using Barcode drawer for iPhone Control to generate, create ANSI/AIM Code 39 image in iPhone applications. Printing DataBar In Java Using Barcode drawer for Java Control to generate, create GS1 DataBar Truncated image in Java applications. Conductance and the siemens
Draw GS1  13 In Java Using Barcode encoder for Java Control to generate, create EAN 13 image in Java applications. Encoding Code 3 Of 9 In None Using Barcode drawer for Online Control to generate, create Code39 image in Online applications. The better a substance conducts, the less its resistance; the worse it conducts, the higher its resistance. Electricians and electrical engineers sometimes prefer to speak Encode UPC Symbol In None Using Barcode encoder for Excel Control to generate, create GS1  12 image in Excel applications. Matrix Barcode Maker In Visual Studio .NET Using Barcode printer for Visual Studio .NET Control to generate, create Matrix Barcode image in Visual Studio .NET applications. Power and the watt 29 about the conductance of a material, rather than about its resistance. The standard unit of conductance is the siemens, abbreviated S. When a component has a conductance of 1 S, its resistance is 1 ohm. If the resistance is doubled, the conductance is cut in half, and viceversa. Therefore, conductance is the reciprocal of resistance. If you know the resistance in ohms, you can get the conductance in siemens by taking the quotient of 1 over the resistance. Also, if you know the conductance in siemens, you can get the resistance in ohms by taking 1 over the conductance. The relation can be written as: siemens ohms 1/ohms, or 1/siemens Smaller units of conductance are often necessary. A resistance of one kilohm is equal to one millisiemens. If the resistance is a megohm, the conductance is one microsiemens. You ll also hear about kilosiemens or megasiemens, representing resistances of 0.001 ohm and 0.000001 ohm (a thousandth of an ohm and a millionth of an ohm) respectively. Short lengths of heavy wire have conductance values in the range of kilosiemens. Heavy metal rods might sometimes have conductances in the megasiemens range. As an example, suppose a component has a resistance of 50 ohms. Then its conductance, in siemens, is 1 50, or 0.02 S. You might say that this is 20 mS. Or imagine a piece of wire with a conductance of 20 S. Its resistance is 1/20, or 0.05, ohm. Not often will you hear the term milliohm ; engineers do not, for some reason, speak of subohmic units very much. But you could say that this wire has a resistance of 50 milliohms, and you would be technically right. Conductivity is a little trickier. If wire has a resistivity of, say, 10 ohms per kilometer, you can t just say that it has a conductivity of 1/10, or 0.1, siemens per kilometer. It is true that a kilometer of such wire will have a conductance of 0.1 S; but 2 km of the wire will have a resistance of 20 ohms (because there is twice as much wire), and this is not twice the conductance, but half. If you say that the conductivity of the wire is 0.1 S/km, then you might be tempted to say that 2 km of the wire has 0.2 S of conductance. Wrong! Conductance decreases, rather than increasing, with wire length. When dealing with wire conductivity for various lengths of wire, it s best to convert to resistivity values, and then convert back to the final conductance when you re all done calculating. Then there won t be any problems with mathematical semantics. Figure 25 illustrates the resistance and conductance values for various lengths of wire having a resistivity of 10 ohms per kilometer.

