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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

UFS responds to concerns around high costs of higher education

2015-10-15

Dear Students

UFS responds to concerns around high costs of higher education

There is an understandable and shared concern among students in the country around the high costs of higher education. As you know, this also is a matter of deep concern on our campuses, which the University of the Free State (UFS) has made a priority in discussions with student leaders - and through new strategies to relieve the burden of costs on poor students and their families. In fact, in the past two weeks, the UFS leadership has again engaged students on the matter of fees in the future.

This is what we have done so far. We have maintained our position as one of the universities with the lowest tuition fees in the country. As you would have seen from recent newspaper reports on the cost of a degree at various institutions over the past five years, the UFS has had consistently low fees. This is not an accident; both the University Council and the executive leadership of the UFS is of one mind that we must offer a high quality education at minimum cost to all our students, despite the rising costs of operating a large multi-campus university with 30 000 students. Our commitment to you is to continue to keep those costs to students as low as possible, without compromising on the quality of education.

In addition, we took a decision earlier this year to become the first university to drop application fees for first-year students. We are proud of that achievement, since so many students fall at this first hurdle as they contemplate post-school education and training. We also waived registration fees for postgraduate students and now Research Master’s and PhD students can study tuition free under certain conditions. We raised more than R60 million from the private sector to enable talented students, who do not receive NSFAS funding, to complete their degree studies at the UFS. We set aside some of the university’s own funds to enable even more students to access finance for their studies. And we now have a special office set aside to counsel and assist students to apply for more than one scholarship to support their studies. The university does not follow a policy of maximizing exclusions. It has endeavoured and succeeded to turn around the majority of its potential deregistration cases. During 2015 we had 2 700 students at the risk of being de-registered, but our serious efforts resulted in only over 200 instances of exclusion we could not mitigate. As is the practice for the past few years, these students’ debt for 2015 has been reversed.

But, we do not only look for funds from outside to support our students. Last year we set up a Staff Fund to which ordinary members of the academic and support staff can contribute from their own, and sometimes very modest, salaries to enable Kovsie students to finish their degrees. We have volunteers who work on the No Student Hungry (NSH) Bursary Programme to raise funds for students who cannot afford a regular meal. We have an open line to rural and township schools to nominate poor students with good results for support by the Rector’s Fund, and some of those students are now in their final year of studies. And many of our staff support individual students in their homes and with their families, without being asked to do so. This is what we call the Human Project and it remains central to the way in which we deal with students.

We will of course continue to make representation to government, the private sector, and individuals to increase funding, especially for first-generation students, and for families where more than one student is at university. We will continue to take to the road to raise funds from companies and foundations to finance our students. We will expand on-campus opportunities for limited working hours for students who wish to earn some money to support their studies. As we have said often before, no student who passes all their courses or modules will be turned away simply because they do not have the funds to study.

The UFS discusses and agrees to fee increases with our students well in advance of the next academic year. None of these decisions are taken without the agreement of the student leadership and thus far these engagements, while tough, have always been done in good faith and with the students’ interests at heart.

It is important for you to know that, with the declining government subsidy, in real terms, and the expanding needs of our students, we will not be able to keep the university running without fees - even though this source of revenue comes mainly through scholarships and bursaries. We need to compensate staff, purchase new library books and renew journal subscriptions (which is very difficult given the low value of the Rand), upgrade computers and software, pay rates and taxes, purchase laboratory equipment, pay the water and electricity bills, expand internet services, upgrade campus security, and hire more academics to keep class sizes reasonably small. It is important for you to know that the university has managed to avoid increasing student fees as a result of much higher municipal rates. Our lecturers are not the highest paid in the country and financially we run a tight ship. We consistently achieve unqualified audits and we are known to be one of the universities that manage its NSFAS contributions with great efficiency. We do this because of our commitment to ensure that our students are able to enjoy a high quality of education on a stable campus where there is a deep respect for all campus citizens.

Despite all these efforts, the most important message we wish to communicate, is that the door remains open for continued discussion with student leaders as we continue to find ways of keeping university education open and accessible to all qualifying students. At the same time, the UFS leadership is involved in discussions with government about how to best manage the escalating cost of higher education for our dents.

Thank you for your support and understanding at this time and be assured, once again, of our commitment to students as a matter of priority to the university leadership.

Best regards

Prof Jonathan Jansen
Vice-Chancellor and Rector

University of the Free State
19 October 2015

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