St Pat’s physics students ride soundwave success

Students at St Patrick’s College Sutherland have reached a new depth of knowledge about sound waves with projects that visualise and test the science behind them.

The class of 21 Year 11 students completed the experiments for the depth studies component if their preliminary HSC Physics course, which asked them to explore an area of interest from the syllabus independently.

Inspired by her love of string instruments, Anna Dau used string and a vibration generator to model a standing wave – a vibration of a system where some points remain fixed while others between them vibrate with the maximum amplitude.

The classically trained pianist, who also plays cello and saxophone, said the experiments helped her appreciate how interrelated maths and music were.

“I always though music and maths were separate things but then I realised that I love both of them because they’re connected,” she said. “The harmonics series has a fundamental frequency, which is the note that’s heard the most, and it also has overtones. I investigated how they are made, which made me appreciate them more. Physics does force you to think differently.”

Thomas Ryan and Billy Thoroughgood found a way to translate soundwaves into light patterns to measure how amplitude affects their frequency. They placed a speaker in a bowl and used a balloon and mirror over them to shine laser-like patterns on a wall, created by different frequencies.

How they problem-solve … shows perseverance and sometimes a lot of creativity.

– Jennifer Ming

“It let you visualise what the sound wave is,” Thomas said. “When you played pure tone it would make a shape that you could measure, and it would make a different shape depending on what frequency was being played through the speaker.”

Billy said it was difficult to reproduce the set up, but their experiment results followed the same pattern.

“There was always exponential growth from each frequency as you increased the amplitude,” he said. “When you added two different frequencies they were more alive than the single frequencies, and if you were careful you could hear the beats from the merging waves.

“It’s quite interesting how frequencies work and how you can display how they interact. You can’t always get it the same every time. You might play 100 hertz and get a nice big figure eight pattern, but the next time you play that you may get a tiny circle.”

The College’s Science co-ordinator, Jennifer Ming, said apart from encouraging strong communication skills and a team environment, Physics helped students to embrace challenge and become good thinkers.

“It is not a course you can take and memorise concepts,” she said. “Students need to apply their knowledge to unknown situations readily, which is a useful skill in the working world as we know things do not always go to plan.

“I am impressed by how they problem-solve to adapt their experiments to try to get results.  It shows perseverance and sometimes a lot of creativity.”

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