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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

Kovsie artists to rock at Vryfees

2014-06-18

Photo: Conrad Bornman

It is the dead of winter in the heart of the Free State. The Vryfees is laying full steam ahead.

However, the talent that makes of this annual arts festival such a phenomenal success doesn’t only come from outside of our Bloemfontein Campus. This year’s productions will abound with performances by Kovsie staff, students and alumni from our Department of Drama and Theatre Arts.

Behind the scenes, our people will also play a vital role in the achievement and progress of the festival. Prof Luwes is a member of the festival committee and together with Dr Venter and Godfrey Manenye, he also serves on the artistic selection committee for theatre.

Thys Heydenrych, lecturer in the above department, was appointed as the technical manager of this year’s Vryfees. This means that he is in charge of the placement and assigning of venues for productions on campus. All the technical aspects for these venues rest on Heydenrych’s shoulders. For this huge task, he is supported by a team of technical staff which includes mostly students.

Take a look at the list of all our Kovsie artists who are working hard to make the 2014 Vryfees better than ever:

Don Juan onder die Boere
Lecturers: Walter Strydom, Gerben Kamper (director),
Students: Mark Dobson, Michael Garbett, Helet de Wet
Former students: Marijda Kamper (Wynand Mouton theatre manager), Ilne Fourie, Hilletje Möller, Chanmari Erasmus, Michelle Hoffman, An-Mari Loots, Madré van Straten

S(t)out en Peper
Lecturers: Dr Pieter Venter (director), Thys Heydenrych
Former students: Ilne Fourie, Michelle Hoffman

Nag van die Hiëna
Head of Department: Prof Nico Luwes (author and director)
Lecturers: Gerben Kamper, Minette Grové
Former students: Carel Nel, Lindy-Lee Kleynhans, Ilne Fourie, Angelo Mockie (staff member at Student Affairs)
Student: Peter Taljaard (PhD student)

Rondomskrik
Former student: Chrystal-Donna Roberts (currently Pasella presenter and previously on the set of 7de Laan)

Slaaf
Former student: Carel Nel

Te Veel vir ? Coloured Girl
Former students: Angelo Mockie (staff member at Student Affairs), Olivie Sauer

The Bar
Lecturer: Godfrey Manenye (director)
Former students: Angela Edwards, Jane Mpholo
Students: Yoliswa Jacobs and Luandro Carstens

Victoria se Geheim
Lecturer: Dr Pieter Venter (director)
Former students: Chanmari Erasmus, Carel Nel, Gené McCaskill, Michelle Hetzel
Students: Helet de Wet, Marli van der Bijl (NRF Magister Intern), Jana Coetzer, Marnel Bester

Een Kleine Lientjie
Lecturer: Walter Strydom
Former student: Anna Visser (author and director, OFM presenter)
Students: Marli van der Bijl, Charl Henning, Jana Coetzer

For more information on the productions or the Vryfees programme, follow this link:
http://www.vryfees.co.za/

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