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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

Ensure your place at the UFS

2010-10-27

The University of the Free State (UFS) appeals to all prospective South African students who want to come and study at the UFS in 2011 to submit their applications no later than Tuesday, 30 November 2010.

The UFS is aware of the fact that learners will not have received their final Grade 12 results by Tuesday, 30 November 2010; therefore provisional admission will be granted based on learners’ most recent Grade 12 results. Final admission will take place upon receipt of the final Grade 12 results, which will be available early in January 2011.

Prospective students can obtain application forms for admission at the following places:

The UFS’s web site at www.ufs.ac.za,
The Information Office (Unit for Prospective Students) at the Thakaneng Bridge on the UFS’s Main Campus in Bloemfontein,
You may also send an e-mail to info@ufs.ac.za or
Phone 051 401 3000 and the necessary forms will be posted to you.

Senior undergraduate students (that is all students who were registered up to and during 2010 at the UFS) as well as post-graduate students, must self-register electronically on-line from Monday, 1 November 2010 until Tuesday, 4 January 2011. This includes master’s and doctoral students.

In order to encourage senior students to register online, the UFS offers 20 laptops as incentives for the senior students who successfully register online from 1 November 2010. These laptops will be handed over to the winners after the registration process in 2011.

Registration of first-year students:

The Rector and Vice-Chancellor, Prof. Jonathan Jansen, will welcome first-year students on Friday, 14 January and Saturday, 15 January 2011, respectively, in the Callie Human Centre. The Faculties of Economic and Management Sciences, the Humanities and Education will be welcomed on 14 January 2011 and the students of the Faculties of Natural and Agricultural Sciences, Law and Theology shall be welcomed on 15 January 2011. The compulsory orientation programme for new first-years will also then commence.

From 17 to 21 January 2011 first-year students will receive academic advice at the Callie Human Centre, whereafter they will be referred for self-registration. These processes will take place according to the set timetable. This timetable is available in the Kovsie Guide that will be sent to learners as soon as we have received their applications, as well as on the web site of the UFS at www.ufs.ac.za/register2011.

First-year students’ fees must be paid prior to arrival on 14 and 15 January 2011.

Registration of senior students:

Senior students who experience problems with the electronic on-line self-registration process have the opportunity to resolve problems within a programme on campus from Wednesday, 5 January until Wednesday, 12 January 2011. This programme will be sent out to students and is also available at www.ufs.ac.za/register2011. The specific scheduled day for senior students to resolve problems is the last and only day to resolve the problem.

Senior students can also contact 051 401 9111 for more information in this regard.

Students may register for prescribed modules for 2011, even though the November 2010 examination results are not yet available. Changes resulting from examination results that are made available later can be done up to and including 28 January 2011.

In terms of applications for senior students, only students who have interrupted a calendar year of study need to re-apply for admission.

Registration of students at the UFS’s Qwaqwa Campus:

Senior and first-year students of the UFS’s Qwaqwa Campus register from Wednesday, 12 January until Friday, 28 January 2011 in the Nelson Mandela Hall on this campus.

Registration of students at the UFS South Campus:

First-year students from the UFS’s South Campus in the University Preparation Programme and the Extended Programme (only Natural and Agricultural Sciences) register from Monday, 24 January till Friday, 28 January 2011 in the Arena Hall on the South Campus.

Students who have successfully completed the University Preparation Programme register with the first-year students on the UFS Main Campus on Friday, 14 and Saturday, 15 January 2011 – according to faculties (cf. paragraph 6).

Lectures for all students shall commence on Monday, 24 January 2011.

MEDIA RELEASE
Issued by: Lacea Loader
Director: Strategic Communication (actg)
Tel: 051 401 2584
Cell: 083 645 2454
E-mail: loaderl@ufs.ac.za
26 October 2010

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