Reply To: Interesting Practical activities on waves

[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