Transverse Sine Wave Maker Notes

The Transverse Sine Wave Maker Interactive is an adjustable-size file that displays nicely on smart phones, on tablets such as the iPad, on Chromebooks, and on laptops and desktops. The size of the Interactive can be scaled to fit the device that it is displayed on. The compatibility with smart phones, iPads, other tablets, and Chromebooks make it a perfect tool for use in a 1:1 classroom.

In very simple terms, we like to think of an oscillator as something that wiggles back in forth while maintaining the same central position. Oscillators wiggle in time. This is very simply put but put in a language students can understand. And once again, simply put, we like to think of a wave as a collection of coordinated wigglers extended across space. If a vibrating object is a wiggle in time, then a wave is a wiggle in time and space. The language is simple but finding a system to demonstrate it to students takes some work and often involves a high potential for making a mess. A paint bucket oscillating as a pendulum and dripping paint (or sand) on moving butcher paper (dragged by a constant speed vehicle) is a great demonstration but leaves a mess that most teachers don't want to deal with. And a collection of several synchronized pendulum bobs of varying length does an equally good job of highlighting the connection between periodic motion and wave motion. While it's not a mess, it is a chore to set up and the first period is likely to destroy it for the periods that come after. And then there's the gum drops attached to the end of shish-ka-bob skewers that are then taped to a long strip of masking tape and stretched out the length of the classroom. It's also very mesmerizing, laborious to set up, and subject to rapid, exponential decay.

Perhaps we can offer a solution to the mess and the chore - the Transverse Sine Wave Maker. The oscillating turntable and attached marker provide a display of a wiggle in time. The nature of that wiggling can be modified by two sliders - a frequency slider and an amplitude slider. The marker leaves a trace of its up and down wiggles on a sheet of butcher paper. And to extend the wiggling across space, the butcher paper can be moved. This transverse movement is controlled by the paper speed slider. The oscillating system and butcher paper can be paused and a background grid can be used to make measurements of the length of the oscillating pattern (wavelength). The background grid is composed of 1-meter squares with subdivisions every 0.2 meters.

This Interactive could be suitably used at just about any stage of a learning cycle on waves and sound. Numerous wave concepts are illustrated in the Interactive and a study of the numerical relationship between speed, wavelength, and frequency is easily done. That being said, we have provided a Student Activity Sheet that provides a more directed experience. View Wavelength-Frequency-Speed Activity. The activity has two parts. The first part is qualitative in nature and has students changing speed, frequency, and amplitude to determine how increases in each affect (increase, decrease, or no affect) the wavelength. The second part is quantitative and involves a good deal of data collection and analysis. Students modify frequency and collect wavelength values at a constant speed to determine an equation relating frequency and wavelength. We suggest use of this Desmos file - https://www.desmos.com/calculator/528tlomstv - to plot data, determine the best fit curve, and to write an equation for the data. Then students modify speed and collect wavelength values at a constant frequency to determine an equation relating speed and wavelength. We suggest use of this Desmos file - https://www.desmos.com/calculator/xyxk07wdzv - to plot data, determine the best fit curve, and to write an equation for the data. The activity ends with students identifying an equation and ... "Then (and most importantly) present evidence and use reasoning based on the findings of this activity to support the claim you are making." While the equation is definitely google-able, the evidence and reasoning is not (at least not at this writing).

There are numerous resources at The Physics Classroom website that serve as very complementary supports for the Transverse Sine Wave Maker Interactive. These include:

 

 

Additional resources and ideas for incorporating Transverse Sine Wave Maker into an instructional unit on waves and sound can be found at the Teacher Toolkits section of The Physics Classroom website. Visit Teacher Toolkits.