Degrees of phase

Chapter Degrees of phase

Teach Yourself Electricity and Electronics Third Edition Book
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Teach Yourself Electricity and Electronics Third Edition Book

  • it will stop and turn around again. This will go on and on, with a frequency of 1 Hz, or acomplete cycle per second, because you are swinging the ball around at one revolutionper second.218 Phase12-3Swinging ball and string.At A, as seen fromabove; at B, as seenfrom edge-on.If you graph the position of the ball, as seen by your friend, with respect to time, theresult will be a sine wave (Fig. 12-4). This wave has the same characteristic shape as allsine waves.It is true that some sine waves are taller than others, and some are stretched outhorizontally more than others. But the general wave form is the same in every case. Bymultiplying or dividing the amplitude and the wavelength of any sine wave, it can bemade to fit exactly along the curve of any other sine wave. The standard sine wave isthe function ysin x in the (x,y) coordinate plane.You might whirl the ball around faster or slower than one revolution per second.The string might be made longer or shorter. This would alter the height and or the fre-quency of the sine wave graphed in Fig. 12-4. But the fundamental rule would alwaysapply: the sine wave can be reduced to circular motion.Degrees of phaseBack in Chapter 9, degrees of phase were discussed. If you wondered then why phase isspoken of in terms of angular measure, the reason should be clearer now. A circle has 360