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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

Getting out of the dark

2015-04-28

Photo: Leonie Bolleurs

Since 2008, the University of the Free State has been busy with the planning and implementation of projects to reduce the impact of load shedding. To date, the cost of these projects has run to R6 million. They have been done primarily to ensure that the academic programme does not suffer damage as a result of the increasing interruptions in the power supply that are continuing this year.

The university’s greatest concern has been the provision of emergency power to the lecture halls and laboratories.

Thus far, 35 generators are servicing 55 buildings on the three campuses of the UFS. This includes 26 generators on the Bloemfontein Campus, eight on the Qwaqwa Campus in the Eastern Free State, and one generator on the South Campus in Bloemfontein. The generators are already in service, and are maintained in working order.

Since 2010, the university has also ensured that all newly-built academic buildings are equipped with emergency power supplies.

On the South Campus in Bloemfontein, the new lecture-hall building and the computer laboratory are equipped with emergency power, while the installation of emergency generators in other buildings is under way. The majority of the buildings on the Qwaqwa Campus in the Eastern Free State are equipped with emergency power supplies.

In the meantime, the UFS management has approved a further R11 million for the installation of additional generators on the three campuses. A further R1.5 million has also been approved for the purchase of two mobile generators.

To extend the work already done, the main task will be the installation of more generators on the Bloemfontein Campus to ensure that lecture halls with emergency power will be available for the centrally-arranged timetables, and to ensure that more of the critical laboratories will be provided with emergency power.

There are still some important buildings and halls on the Bloemfontein Campus that must be supplied with emergency power. However, it is a costly process and must be brought into operation gradually. The further implementation of emergency power depends on the delivery of equipment. The university is also investigating alternative solutions for power provisioning, including solar power.

Generators with spare capacity are optimally deployed to satisfy the lower needs of the campus, including the Odeion, the ANNEX at Microbiology, the Stabilis ANNEX, the Agriculture Building, the UV-Sasol library, and the Francois Retief Building.

In addition, the UFS is busy on all campuses, coupling area lighting, including

street lights and pedestrian walkways, to existing generators. Procedures for the operation of mechanical equipment, such as entrance gates, lifts, and so on, are currently being dealt with on all campuses. Continuous power sources for certain ICT equipment will be installed on all campuses to protect it against power surges.

Staff and students can also equip themselves with the necessary knowledge to manage load shedding in their specific areas of work and study. It is always helpful to know who to contact. The following list with guidelines and contact numbers has been compiled to assist you:

1. In an emergency, call Protection Services. This line will continue to operate, regardless of whether the power is on or off.
2. Avoid using lifts just before planned load shedding. Some lifts have emergency power packs which will bring the lift to the nearest floor and open the doors. If you still get stuck in a lift during a power outage, use your cellphone to call Protection Services. While you're waiting, stay calm and be patient.
3. If the access control systems in your building stop working after load shedding, contact Protection Services.
4. The students and staff members who are most at risk during load shedding are those in wheelchairs or with other mobility limitations. As far as possible, plan ahead to avoid being stuck on a floor or in a room that is difficult to access when load shedding is imminent. Please contact Protection Services if you need assistance.
5. During a fire, alarms WILL go off. Alarms are not power driven, but battery driven. For assistance, contact Protection Services.
6. The main UFS Switchboard (Bloemfontein Campus +27(0)51 401 9111 and Qwaqwa Campus +27(0)58 718 5000) will continue to operate during load shedding.

Contact details of Protection Services:

Bloemfontein Campus: +27(0)51 401 2634/2911
Qwaqwa Campus: +27(0)58 508 5460/5175
South Campus: +27(0)51 5051217

Communication and Brand Management will make information available on the UFS web, Facebook page, Twitter, Blackboard and the intranet. Get the load shedding schedule from Eskom’s webpage (http://loadshedding.eskom.co.za/). The Bloemfontein Campus falls in group 4 and the South Campus falls in group 2 in Centlec’s load shedding schedule.

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