Interesting Practical activities on waves

[Paul McGlynn]

Having been asked by a college with a large STEM budget for some suggestions for equipment, I have been approached by KIOSC at Knox to develop some practical activities that they can offer to students in VCE when I offered a Kundt’s apparatus might be a interesting way to demonstrate standing waves. I am now thinking of other equipment that schools might not have the capacity to purchase and/or the knowledge to use that would allow more hands-on experiments in the waves/light and matter areas.
Things that come to mind are;
Kundt’s apparatus for standing waves and resonance, speed of sound (what else), Chlandi plates for 2D standing waves, vibration generators to produce waves in strings, ripple tanks for behaviour of waves (often in schools but usually in bits), reproducing Young’s experiment with multiple coloured lasers, demonstrating cathode ray tubes with induction coils (again often in schools but nobody knows how to use them).
Are the photoelectric kits worth it or are simulations just as good?
Any other ideas of experiments or demonstrations that could be done if you had the money for the equipment and time to plan? Doesn’t have to be in this area.

[Man Lam]

Hi, Paul
I have some experience in developing experiments/demos and would like to share some of my vision on this matter.

1. Barton’s Pendulum will be good to show resources. If you have some old ball and ring old equipment that laying around, you can ask students to make their ones with paper, strings. But make sure you have a good coupling between the metal ball and the paper ball. (a small piece of wood will be good)

2. Natural frequency. https://www.youtube.com/watch?v=yVkdfJ9PkRQ I was aiming to build one by myself a year ago but then I found they were selling it in china. So I bought one for myself instead of building one.

3. Using signal generator to create standing wave from two speakers. Students can walk across the classroom to hear different amplitude at different positions.

4. Again using a signal generator to create beats from two speakers.

5. ultrasonic cleaner to show the compressive wave and the wave profile. This can actually visualize how ultrasound works.

6. If you have time, you can create a Edison sound recorder by aluminium foil. Should be quite fun to see kids shouting to paper cups.

7. You may use a cigarettes lighter, some naked copper wire with aluminium foil to reproduce Hertz experiment. I managed to light up a small LED instead of a spark. But make sure you have a really dark room.

8. You can use two polarizers and a acrylic tube ~60mm id to show the invisible disc. Similar sculpture in the reception of Synchrotron. I built one myself. Quite easy to build.

9. Coherer. Remember to use a pure DC source not the IEC power supply. It will show EM wave actually carry energy.

10. Ruben tube will be another interesting way to show frequency and wavelength. Although you can make one from soft drink bottle but better to get a commercial one which is much safer.

11. You may also want to have some lasers with different frequencies when doing double slits experiment. But keep in mine that some lasers are dangerous. Use them with extra care and demo only!!! It is illegal to possess lasers with output power >=0.1 mW without a licence. I know some teachers love them especially showing how to pop balloons. Just don’t.

These are what I have in mind at this stage. Give me a shout if you need further information.

Cheers

Man Lam

[Man Lam]

One more experiment that you can do it is to use amplitude modulation of light to transmit sound. This experiment can show the amplitude of light. There is a commercial product on the market already but I prefer to ask students to build their own ones.

Materials/equipment:
a little solar panel
LED light torch or 3W LED or solid state red laser
3.5mm jack
self powered speaker

[Paul McGlynn]

Thanks for the ideas. SOme I have tried or seen before but will have a play with the others.

[Paul McGlynn]

Playing around with Kundts apparatus. Suggestions for replacing cork dust, which doesn’t seem available anymore, for making antinodes visible.

[Author]

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