Parabolic Reflectors from the time period before Christ till the future

We often see telecomunication systems with huge parabolic satelit discs and antennae. How did Man discovered their usefulness? When did it start? I like to begin with a simple question. How did Roman emperors communicate with their many citizens back in the good old days before the invention of the PA systems or electricity? Well the answer lies in the unique buildings they built. You may be familiar with one particular such famous building in Rome. It is the Colisuem. And it has a unique shape which is termed parabola. I usually teach via an activity. Look at the picture of Year 10 students carrying out an activity with wine glass during our online class

This unique shape is excellent for transmitting sound if the emperor was at the focal point. To demonstrate this, students or teachers carry out the wine glass experiment. The wine glass is filled with water and a finger is pressed on the rim whilst moving it around. A loud sound will be produced due to the unique parabolic shape of the wine glass. I made a short video for you so you can watch and produce the sound. I will put the video links and picture links in the Google classroom that I have set up. Learning has to be experiential. What process are involved to produce the sound? The main process is reflection of sound from the parabolic reflector.This was what the Roman emperors used to communicate with their many citizens. When travelling overseas, I make a point to visit amphithertres and enjoy the miraculous effect of sound transmission.

This is one of me in Athens in Greece.The biggest amphithertre I have been in is the ancient one in Ephesus in present day Turkey. It seats 26,000 people and it still work. During the pandemic, I could not travel to East Malaysia to teach due to the lockdown. I used Zoom and Google Meet to teach the teachers of SK Methodist Kapit the parabola lesson. I was most happy when the teachers sent me videos of thir students having learnt how to do this activity. Now that I have learned and am using Google Classroom, I can see immense potential to teach more online classes and I am quite excited

While we can hear the sound, we cannot see the sound waves so this process of reflection is best demonstrated by using a parabolic mirror and light rays from the Hodson Light Box Kit