Physics Help Forum lissajous curves/figures

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 Jul 11th 2019, 07:11 AM #1 Junior Member   Join Date: Jun 2019 Posts: 1 lissajous curves/figures I have found myself in a position where i need to learn more about lissajous curves/figures. I have come across them before but only ever setup equipment to show the different types of patterns. I now need to understand more on how to use and interpret a lissajous in a practical sense as in how to make sense of the patterns when hooked up to a circuit. Can anyone explain how a lissajous is used and how to make sense of the images produced. Or maybe point me in a direction that may help me to learn more about them with out going too glass eyed?
 Jul 11th 2019, 09:31 AM #2 Senior Member   Join Date: Aug 2010 Posts: 418 What have you already looked up about them? It has been a very long time since I dealt with Lissajous figures but a Google search gave several websites. This one: https://www.bing.com/search?q=lissaj...&setlang=en-US defines them as "graph of a system of parametric equations x=Asin(at+δ), y=Bsin(bt)" (I hadn't remembered the "$\displaystyle +\delta$", I just used x= A sin(at) and y= B sin(bt) so the curves all passed through (0, 0).) topsquark likes this.
 Jul 11th 2019, 10:26 AM #3 Senior Member     Join Date: Jun 2016 Location: England Posts: 932 Alternatively try: "any of a number of characteristic looped or curved figures traced out by a point undergoing two independent simple harmonic motions at right angles with frequencies in a simple ratio." This gives a hint toward the type of usages I have seen them used for, comparing the characteristics of two (related) signals. If you feed a sinusoidally varying signal into the X channel of an oscilloscope and a different sinusoidally varying signal into the Y channel of the oscilloscope then it will display Lissajous figures. The pattern of the figure has a direct relationship with the frequency differences of the signals topsquark likes this. __________________ ~\o/~

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