The Physics Teaching Podcast

Ways to teach… Waves

Thomas, Robin and Patrick introduce and discuss many ways of teaching waves that have been shared by the listener.

Timestamps

  • Physics in the News – Blue Origin @ 01:07
  • Ways to teach… Waves @ 01:50
    • Cara Wood and a piece of string @ 02:20
    • Slinkys @ 06:50
    • Making many nodes @ 10:54
    • Salt Pendulum @ 13:47
    • Acetates @ 14:58
    • Jed’s wave visualisation experiment @ 16:48
    • How to remember the difference between Transverse and longitudinal @ 18:59
    • Alom Shaha and the Jelly Baby Wave Machine @ 20:17
    • Standing waves @ 24:51
    • Ruben’s Tube and Kundts Tube @ 28:01
    • Showing colour mixing and projector polarisation @ 30:43
    • Young’s slits – lab scale with sound @ 32:47
    • PhEt @ 33:38
    • Mexican Wave @ 34:20
    • Tell us misconceptions! #tptpmisconception @ 35:25
    • Who won Alom Shaha’s Book? @ 37:43

Summary

Patrick, Thomas and Robin get together to tackle ways to teach waves but not until they have touched on Jeff Bezos’ bid for extra-terrestrial adventure: Blue Origin.

Cara Wood was first up sharing tips for teaching waves.  She introduces waves by simply getting students to pluck a piece of string held in their teeth, so that they can see, feel and hear vibrations, experience amplitude and frequency, and discuss waves travelling through solids and gases.  Patrick loved this: really giving a tactile encounter with waves and their source.  Robin made the tenuous link to cochlear implants.  Very similar is the metal coat hanger demo.

“You can’t beat a Slinky” according to Dan Toomey – thanks Dan!  Patrick put us onto “Snakey springs” on amazon for a mighty £27, but we found them cheaper with a bit of persistence: £5.75 at Select School Supplies. Snakey Springs help to avoid Slinky tangles when demo-ing transverse waves.  Thanks to Graham Thomson for the tip of setting a ball next to the slinky spring so that it gets struck as the wave passes and you can thus link frequency and energy.  Graham pointed out the rich discussions you can have on time period, frequency, wave speed and wavelength all with the Slinky.  Thomas was really impressed with Frank Noschese’s video using paper cups next to the Slinky to demonstrate constructive and destructive interference.  Robin recalled a similar method to this to demonstrate the vibrational link to sound waves.

Frank Noschese masters the Slinky

Thanks to Dr Joshua Griffiths and Graham Thompson who talked about challenging students to produce features on ropes and Slinkies, such as increasing numbers of standing waves and purposely frustrating by asking for high frequency, long-wavelength waves.  This gives a good discussion of why it can’t be done!

Thanks to all the other folk too numerous to mention, who also pointed us towards the Slinky as a ‘must-have’ for teaching waves.

Thanks to Dan Toomey for the salt / sand pendulum video.  Thomas was delighted to report he had already done this and Patrick was keen to have a go.

John Hamilton’s use of acetate wave traces to demonstrate superposition makes a tough concept much easier for students to visualise – thanks John!  Jed Marshall uses acetates to get across the tricky idea of wavefronts, alongside his ripple tank that students can struggle with and he kindly supplied a booklet to show how it worked. (photos below).

  • Thanks to John Hamilton
  • Thanks to John Hamilton
  • Thanks to Jed Marshall
How’s this for a handy mnemonic for longitudinal vs. transverse?  Thanks to Chris Beason and K Physics 1.

Alom Shaha joined us for his PIM and he described his jelly baby wave machine. The video says it all: easy to make, and as Alom says, transformative in the teaching of waves! Reflection, refraction, amplitude and frequency – all easily demo-ed quickly and cheaply. Despite Jelly Babies being lost in translation, Patrick endorsed the machine and he still uses it, although the Gummy Bears may be past their sell-by date!

Signal generators, strings and vibration generators always go over well, particularly in conjunction with a stroboscope and Patrick described how he challenges students, not least through atmospheric use of Pink Floyd music! Don’t forget your Rubens tube too – it really helps discussing pressure differentials in sound waves. And if anyone has any tips to get the Kundt’s tube to work, let us know!

Paul from @PlanetReynolds on Twitter had a lovely dichromatic crystals demo which has “Wow factor” and his toppling dominos is a great way of demonstrating density’s effect on wave transmission. Just search on eBay for “optical glass cube” and “100 led finger lights“.

Thanks again to Dan Toomey for his tip on using superposition with loudspeakers, and don’t forget PhET, ripple tanks and “stadium waves”!

…and finally! Well done to Frank Noschese who we picked from the expensively engineered randomised name selection device. Frank will receive a personally signed copy of Alom Shaha’s Recipes for Wonder.

HAVE A GREAT HALF TERM!!

Join in!

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Music

The music is used under the Attribution-NonCommercial 3.0 International License

Thomas

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