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Clips, toys for physics lab
THERE is an old joke about a university Vice-Chancellor bemoaning the cost of his physics department’s expensive gear. “Why can’t you be like the mathematicians?” he pleads. “All they need is pencils, paper and a wastepaper basket. And the philosophers don’t even need the wastepaper basket.”
THIS UNIVERSE
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Clips, toys for physics lab
THERE is an old joke about a university Vice-Chancellor bemoaning the cost of his physics department’s expensive gear. “Why can’t you be like the mathematicians?” he pleads. “All they need is pencils, paper and a wastepaper basket. And the philosophers don’t even need the wastepaper basket.”
If the joke is unkind to the intellectual heirs of Socrates and Plato, the reality can be just as harsh for those hoping to stand on the shoulders of Newton and Einstein: experimental kit really can be prohibitively expensive. Many African schools resort to teaching physics purely theoretically — an approach good enough for exams but of little help with ingraining real understanding. Growth of their own science and engineering base is being impeded by a lack of resources and the will to put them to good use — until now. Over the past few years, current and retired UK teachers have been showing how to carry out enlightening experiments with cheap or makeshift equipment — balloons, paperclips, toy cars and dice — across sub-Saharan Africa. Joe Brock of Collyer’s College in Horsham, West Sussex, first got involved by producing a booklet of experiments and a set of practical kit to help a student who was volunteering in the Gambia. He later began coordinating volunteers in Tanzania himself. The new electricity kit was perhaps the biggest challenge. Brock and his students put together a set of equipment and an accompanying coursebook, with their electronics sets coming to less than £18 a piece. They needed to be durable, and any soldering would weaken the components and risk breakages. The students hit upon the idea of attaching the LEDs, resistors and so on to wooden blocks, and connecting them to each other with paperclips. The power supply is a wind-up torch bought from a local DIY store and adapted by the college’s technicians. “That was the reason we haven’t done electricity in the past — because we couldn’t find a way,” says Brock. “The whole point of the kit is, you know, put this under a tree and we’ll do it.” Previously, the teaching of electricity wasn’t related to real life, and the students couldn’t work out whether school lights were wired up as a series circuit or a parallel one. They’d been taught that a volt is one joule of energy per coulomb of charge, but not what that really means. The booklet and makeshift equipment helped to explain it by showing what happens when, say, a bulb is added or taken away and by comparing electricity with lorries carrying loads: voltage is how many loads there are per lorry and current is their speed. “It was those analogies that made the understanding of electronics a lot easier,” says Dan Mannion, one of a group of Brock’s students who spent their Monday lunchtimes putting the kits together before taking them to the Gambia. The experiments Brock designed for the remainder of the syllabus are simple but effective. Rolling a 99p toy car down a ramp made out of a bit of electrical conduit can help to show that the car’s final velocity depends on the height it started at. A balloon inflated, stretched over a cork and attached to a CD becomes a miniature hovercraft demonstrating frictionless motion — and is much cheaper than buying a £1,000 air track. It does, however, require a flat surface. “Under a tree you’d be struggling,” Brock says. Radioactivity is taught with dice rather than with caesium and a Geiger counter. A hundred or so are repeatedly rolled and all the threes are deemed to be nuclei that have decayed, and are removed from the pot. Drawing a graph of the number of dice remaining against throw number gives the very same exponential curve you’d expect from radioactive decay, from which one can work out the half-life. Taping a plastic straw to a balloon, then threading through a piece of string, fixing it horizontally like a washing line to use as a track, demonstrates Newton’s laws of motion. Schoolchildren in the Gambia inflated the balloons to different levels before letting them go and seeing whose travelled farthest. “Some of them went six or seven metres — because obviously we had a massive bit of string,” says Katie Bashford, another of Collyer’s students. “That was quite a bit of fun, I think. They enjoyed that one.” It’s not just entertainment, though. Estimating the mass of air that was in the balloons by their volume one can show that the air is heavier than the rubber, leading on to a discussion of how this has to be considered in the design of rockets, which have to lift the mass of their fuel as well as themselves. This basic kit comes to £38, but there’s been a pricier recent addition: Meccano. It substitutes for a signal generator that normally sells for around £300, and its cogs, gears and wind-up handle do just as good a job of vibrating a secured piece of string to produce a standing wave. It has the added advantage of being easily fixed if it breaks. As well as putting together the kits, British volunteers are also helping to train African teachers how to get the best out of them — a cultural shift just as important as provision of resources. “The problem is that the teaching style is one of teaching from the front — chalk and talk,” says Roger Green, the former head of physics at London’s City and Islington College, whose efforts helped to set up a teacher-training centre in a Ghanaian fishing community. “They’re not convinced about the value of doing practical work,” he says. Brock compares the current way of teaching to learning Latin, studied as a purely academic exercise with no application to real life. Experimenting, however, makes it more relevant: “Even things like looking at centre of gravity, and seeing these buses with these people loaded up on these old lorries and they’re right up to the top and the thing’s wobbling all over the place and if you go round a corner at more than three miles an hour you’re all going to die.” It appears to be working. Evaluations from trainee teachers are suitably gushing, and in 2010, Mvomero Secondary School in Morogoro, Tanzania, won a national science competition judged by the First Lady, Salma Kikwete. A school from the middle of nowhere beating leading rivals got others interested in the more experimental approach to science, which looks set to be adopted more widely. In rolling out the projects, they’re now reaching even poorer rural communities whose primary concerns are disease and food. But the volunteers aren’t giving out fish: they’re teaching locals how to catch their own. “If you can get this to work, they’re going to be their own scientists; they’re going to be their own engineers; they’re going to understand how Aids is transmitted,” says Brock. And, eventually, their labs will be filled with high-end equipment too. ‘ — The Independent
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THIS UNIVERSE
If we pour out carbonated drink in a glass, it creates big bubbles. But if we again pour out the same drink in another glass, then very few bubbles are formed. Please explain. If we pour out carbonated drink in a glass, it creates big bubbles. But if we again pour out the same drink in another glass, then very few bubbles are formed. Please explain. I suppose you have seldom wondered why some drinks are called carbonated. They are so called because carbon dioxide is dissolved under pressure in the sweetened drink and it makes big bubbles when it escapes on the bottle cap being removed. The pressure drops and the carbon dioxide is soon gone. Only tiny bubbles are seen due to slow escape of the remaining gas. When a fresh drink is poured out in another glass very few bubbles are visible. No large bubbles, of course. Many people call the drink flat because there is little carbon dioxide left to tingle the tongue. Is
it safe to inhale pure oxygen? I suppose the reason we do not inhale pure oxygen at full pressure is because our rate of metabolisation is adjusted to a certain level. Too much oxygen would add too much fuel to the fires burning within us. Temperature would rise and many other balances would be disturbed. I think it is wise to stay more or less close to the rate of fuel burning and temperatures for which we are designed.
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Trends
CHICAGO: Using just her thoughts, a 58-year-old paralysed woman instructed a robotic arm to grasp a cup of coffee and guide it to her mouth where she sipped from a straw, the first drink she has been able to serve herself in 15 years. The woman is one of two patients in the ongoing trial of BrainGate neural interface, an experimental brain-computer interface technology that may one day give paralysed individuals more mobility. UK climate experiment cancelled on patent concerns LONDON: British scientists have abandoned an experiment to test the possibility of spraying particles into the upper atmosphere to stem global warming, largely due to concerns over a patent for some of the technology, the project's leader said. Scientists and engineers from the universities of Bristol, Cambridge and Oxford are behind a three-year, 1.6-million pound geo-engineering project called Stratospheric Particle Injection for Climate Engineering (SPICE). — Reuters |
