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barcode printing using vb.net Pure capacitance in Software
Pure capacitance QR Code Reader In None Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications. Denso QR Bar Code Printer In None Using Barcode generator for Software Control to generate, create Denso QR Bar Code image in Software applications. Imagine placing an ac voltage source across a capacitor. Suppose that the frequency is high enough, and/or the capacitance large enough, so that the capacitive reactance, XC, is extremely small compared with the resistance, R. Then the current leads the voltage by a full 90 degrees (Fig. 148). At very high frequencies, it doesn t take very much capacitance for this to happen. Small capacitors usually have less leakage resistance than large ones. At lower frequencies, the capacitance must be larger, although highquality, lowloss capacitors are not too difficult to manufacture except at audio frequencies and at the 60Hz utility frequency. The situation depicted in Fig. 148 represents an essentially pure capacitive reactance. The vector in the RC plane points just about straight down. Its angle is 90 degrees from the R axis or zero line. Reading QR Code 2d Barcode In None Using Barcode reader for Software Control to read, scan read, scan image in Software applications. QR Code Drawer In C# Using Barcode generator for .NET Control to generate, create QR Code JIS X 0510 image in Visual Studio .NET applications. Currents leads voltage 255
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EAN 13 Creator In None Using Barcode drawer for Software Control to generate, create EAN 13 image in Software applications. Code39 Generation In None Using Barcode printer for Software Control to generate, create ANSI/AIM Code 39 image in Software applications. When the resistance in a resistancecapacitance circuit is significant compared with the capacitive reactance, the current leads the voltage by something less than 90 degrees (Fig. 149). If R is small compared with XC, the difference is almost a quarter of a cycle. As R gets larger, or as XC becomes smaller, the phase difference gets less. A circuit containing resistance and capacitance is called an RC circuit. Making Barcode In None Using Barcode maker for Software Control to generate, create barcode image in Software applications. Draw Barcode In None Using Barcode generation for Software Control to generate, create bar code image in Software applications. 149 In a circuit with capacitance and resistance, the current leads the voltage by less than 90 degrees. Printing Leitcode In None Using Barcode printer for Software Control to generate, create Leitcode image in Software applications. Draw Barcode In Java Using Barcode creator for Java Control to generate, create bar code image in Java applications. 256 Capacitive reactance The value of R in an RC circuit might increase relative to XC because resistance is deliberately put into a circuit. Or, it might happen because the frequency becomes so low that XC rises to a value comparable with the leakage resistance of the capacitor. In either case, the situation can be represented by a resistor, R, in series with a capacitor, C (Fig. 1410). Code39 Generation In Java Using Barcode drawer for Java Control to generate, create ANSI/AIM Code 39 image in Java applications. Bar Code Generation In ObjectiveC Using Barcode encoder for iPhone Control to generate, create barcode image in iPhone applications. 1410 Schematic representation of an RC circuit.
EAN13 Printer In .NET Framework Using Barcode creator for ASP.NET Control to generate, create European Article Number 13 image in ASP.NET applications. Data Matrix 2d Barcode Maker In None Using Barcode creation for Font Control to generate, create ECC200 image in Font applications. If you know the values of Xc and R, you can find the angle of lead, also called the RC phase angle, by plotting the point R jXC on the RC plane, drawing the vector from the origin 0 j0 out to that point, and then measuring the angle of the vector, clockwise from the resistance axis. You can use a protractor to measure this angle, as you did in the previous chapter for RL phase angles. Or you can use trigonometry to calculate the angle. As with RL circuits, you only need to know the ratio of XC to R to determine the 4 and R 7 , you ll get the same angle as with phase angle. For example, if XC 400 and R 700 , or with XC 16 and R 28 . The phase angle will XC be the same for any ratio of XC :R 4:7. Generate Code 39 Extended In None Using Barcode encoder for Word Control to generate, create Code39 image in Office Word applications. Encode EAN 128 In Java Using Barcode generation for Java Control to generate, create GS1 128 image in Java applications. Pure resistance
As the resistance in an RC circuit gets large compared with the capacitive reactance, the angle of lead becomes smaller. The same thing happens if the value of XC gets small compared with the value of R. When you call XC large, you mean large negatively. When you say that XC is small, you mean that it is close to zero, or small negatively. When R is many times larger than XC, whatever their actual values, the vector in the RC plane will be almost right along the R axis. Then the RC phase angle will be nearly zero, that is, just a little bit negative. The voltage will come nearly into phase with the current. The plates of the capacitor will not come anywhere near getting fully charged with each cycle. The capacitor will be said to pass the ac with very little loss, as if it were shorted out. But it will still have an extremely high XC for any ac signals at much lower frequencies that might exist across it at the same time. (This property of capacitors can be put to use in electronic circuits, for example when an engineer wants to let radio signals get through while blocking audio frequencies.) Ultimately, if the capacitive reactance gets small enough, the circuit will act as a pure resistance, and the current will be in phase with the voltage.

