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Jules Antoine Lissajous was a French physicist who lived from 1822 to 1880. Like many physicists of his time, Lissajous was interested in being able to see vibrations. He started off standing tuning forks in water and watching the ripple patterns, but his most famous experiments involved tuning forks and mirrors. For example, by attaching a mirror to a tuning fork and shining a light onto it, Lissajous was able to observe, via another couple of mirrors, the reflected light twisting and turning on the screen in time to the vibrations of the tuning fork. When he set up two tuning forks at right angles, with one vibrating at twice the frequency of the other, Lissajous found that the curved lines on the screen would combine to make a figure of eight pattern.

The ABC logo is a 3:1 Lissajous figure -- if Lissajous wanted to see this pattern he would have to get one of his tuning forks to vibrate three times faster than the other.

Why did the ABC choose a Lissajous figure for its logo?

Well, the ABC is both a radio network and a television network. Before the days of electronic frequency counters, broadcast engineers often used Lissajous patterns to help tune equipment. A Lissajous pattern seemed a good motif, common to both radio and television.

Because the ABC broadcast in both radio and television, it seemed like 2:1 would be a good ratio. (This makes an infinity symbol or a figure of eight lying on its side). But back in 1965, the figure of 8 logo was being used by the University of the Air. So the ABC decided to base their logo a 3:1 ratio.

Today the ABC has three arms:- Radio, Television and Online. so the choice of a 3:1 logo turned out to be very wise!

In the Sim below you can make your own Lissajous patterns. Use the horizontal or vertical sliders to change the pattern. To make the ABC logo, adjust the dot's vertical speed so that it is 3 times faster than its horizontal speed.

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Source URL: https://www.abc.net.au/science/holo/liss.htm