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TED Talks about rainbows

18 April 2022 | Story Leonie Bolleurs | Photo Stephen Collett

“A rainbow is a natural phenomenon, the result of the refraction and reflection of the sun’s rays in drops of rain. As far as mankind is concerned, it’s a perfectly useless object and won’t make anyone money. Yet the poet who said, My heart leaps up when I behold a rainbow in the sky, only put into word the feeling of wonder and excitement we all have when we see a rainbow.”

“Every day I see a rainbow in my work; I do not need to wait to see one in the sky,” says Prof Ted Kroon, Professor in the Department of Physics at the University of the Free State (UFS), who used this phenomenon to introduce the topic of his inaugural lecture: What’s the use of a rainbow.

“Far from being only a colourful spectacle with no practical value, rainbows are useful – and lead to useful things,” he believes.

According to Prof Kroon, one can find examples of real rainbows and rainbow analogies used not only in everyday life, but also in physics. “Besides it being familiar devices in literature, culture, and even marketing, studies of rainbows can yield practical engineering information and may even help us to find new habitable planets,” he says.

Inspired by the many uses of a rainbow

In his lecture, he discussed the basic features of natural rainbows and how they come about. He also explored how the rainbow gives meaning to colour, and how this relates to the temperature of objects. He looked at an array of instances where the rainbow is used; from depicting the life of a star to indicating that we are sick (a thermometer) or when we need to refill a gas cylinder.

Moreover, Prof Kroon pointed out that rainbows are used in computer chips, stress identification, and to transmit internet data through underwater cables of glass fibre. He also referred to how the rainbow was harnessed as an engineering tool to measure refractive index and characterise fine droplet sprays used in industry.

He continues, “Remarkably, the science developed to understand the natural rainbow can be redirected and applied to the optical properties of metallic nanoparticles, allowing the development of nanotechnology. Knowing how the natural rainbow works and its limitations, better systems have been developed to produce rainbows. Such rainbows have been used to discover new elements and to determine the age of the universe.”

As a member of an international community of phosphor researchers who are privileged to work with rainbows every day, he has used them to study the light-emitting properties of materials doped with bismuth. With this project – an initiative with the African Laser Centre taking place between 2016 and 2021 – he collaborated with the University of Khartoum in Sudan and trained a number of its postgraduate students. “My role included the guidance of students and the measurement and interpretation of the light-emitting properties of the materials. Our research during this time, considering more than a dozen materials, was summarised in 34 scientific publications that contributed to a greater understanding of bismuth ions as light-emitting materials,” he explains.

Developing new materials, efficient in emitting blue light

He has been developing luminescent materials since 2006, primarily for general lighting (fluorescent tubes and LEDs) and displays (television, computer, and cellphone screens), as well as niche applications in medical and forensic science.

As part of his current research, he is examining the effect of plasmonic metal nanoparticles on phosphor light emission. He is also exploring materials that absorb infrared light but emit visible light. “For this, I would like to consider the long-term stability of such materials and develop new materials that are more efficient in emitting particularly blue light,” he says.

Prof Kroon holds a C2 rating from the National Research Foundation and has published more than 150 articles and book chapters, obtaining a Scopus h-index of 26.

News Archive

Exciting open day and Albert Einstein program at Boyden Observatory

2005-05-06

National Science Week, which will be held from 7-14 May 2005, is an annual country-wide celebration of science, led by the Department of Science and Technology. The department selected a proposal by the Boyden Science Centre to coordinate a week of activities in the Bloemfontein area as one of the many projects in the country.

The project for Bloemfontein and surrounding areas will be delivered though a collaboration between the National Museum in Bloemfontein and the University of the Free State (UFS), including the Research Institute for Education Planning, the Department of Physics and other departments in the Faculty of Natural and Agricultural Sciences.

The purpose of National Science Week is:

to create awareness of the important role that science play in people’s daily lives;
to encourage our youth to consider studying and improving their performance in mathematics and science; and
to attract more of our youth into science, engineering and technology (SET) careers.

World Year of Physics and Albert Einstein Program at Boyden Observatory

The International Union of Pure and Applied Physics (IUPAP) declared the year 2005 as the World Year of Physics (WYP). In recognition of this declaration, the great contribution of Physics to the development of technology, and its importance in our everyday lives will be featured strongly during the National Science Week 2005.

On Saturday 7 May 2005 there will be a public programme at Boyden Observatory from 15:30 as a contribution to the World Year of Physics. The programme will be presented in collaboration with the Bloemfontein branch of the Astronomical Society of Southern Africa and will include short presentations on astronomy, space exploration and the sun.

The main presentation will be at 19:00 the evening on the life and work of Albert Einstein. The programme will also include observing sessions through telescopes of objects like the sun, Jupiter and Saturn. There will also be an exhibit on Albert Einstein. Attendance is free but booking is required. For bookings, phone 051-4012561.

Public lecture programme:

Next week the following exciting public lectures will be presented as part of the Science Week activities:

Monday 9 May 2005

National Museum:

A discussion on Apocalypse Then: the greatest mass extinction of all time. The lecture will be presented by Dr Jennifer Botha, Paleontologist at the National Museum.
Bookings: 051-4479609 (entrance is free).

UFS campus:

All lectures at Kine 2, Medical Faculty, UFS campus. Follow directions from the DF Malherbe Road entrance.
Bookings: 051-4012561 (entrance is free).

Tuesday 10 May 2005:

A discussion on the Tsunami disaster of 26 December 2004 at 19:30 (UFS campus, Kine 2 Medical Faculty).

Wednesday 11 May 2005:

A discussion on Is there life out there? at 19:30 (UFS campus, Kine 2 Medical Faculty).

Friday 13 May 2005:

A discussion on Hunting Black Holes at 19:30 (UFS campus, Kine 2 Medical Faculty). The lecture will be presented by Dr Phil Charles, Director: South African Astronomical Observatory.

Science awareness day at the National museum

The science week will be concluded on Saturday 14 May 2005 with a special Science Awareness Day at the National Museum, Aliwal Street, Bloemfontein.

The excellent exhibits at the museum will be supplemented with activities, career information and video shows. The duration of the programme will be from 10:00-16:00. For enquiries, please call 051-4479609.

Issued by:  Lacea Loader
   Media Representative
   Tel: (051) 401-2584
   Cell: 083 645 2454
   E-mail: loaderl.stg@mail.uovs.ac.za

6 May 2005

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