Technologies for reducing carbon emissions

An article at NextBigFuture lists "Ten Technologies that should have a big impact on Green house gas Emissions". This provides much material for a discussion with Physics students - though the teacher would likely have some research to do! Most teachers would not have heard of many of these. Some are very relevant to us in Guyana. The 10 technologies are:

1. factory mass produced high rises and skyscrapers
2. black carbon free cookers
3. diesel particulate filters for cars and trucks
4. electrification of vehicles
5. retrofitting existing buildings for efficiency
6. reducing carbon dioxide emissions from concrete
7. scaling up of regular nuclear power and hydro power
8. nuclear fission technology advances
9. slash-and-char agriculture
10. biochar

UNESCO Microscience in Guyana?

UNESCO's Teaching and Learning Packages produced by the Global Microscience Project are currently being looked at with a view to their use in schools here in Guyana. These consist of a lunchbox-sized container of equipment which allows certain basic practical activities to be done - preferably by students. Different packages exist for primary science and for secondary chemistry, biology and physics (electricity).

Caribbean online resources for Physics teachers

These are both online resources for teachers. Both are aimed at Caribbean teachers, not just science teachers. Both have made significant progress but are in need of support. Such online endeavours require a minimum number of members to succeed as well as financial support and both appear to be achieving this. Both encourage teachers to upload material.

The Caribbean Educators Network is described as a "social network" for teachers. It has over 1000 members around the Caribbean and elsewhere. Apparently it is better known in Trinidad (over 300 members) than in Guyana (40+). It is free and there are online resources and events. Worth joining.

Notesmaster is a free portal to learning resources for CSEC teachers and students. It has more resources for Chemistry than Physics - hopefully more will be added soon. More features are promised soon. Worth joining.

Investigating refraction

Here I briefly describe an alternative method of verifying Snell's Law using a semicircular block and pins. Two pins are placed along a radius and a third pin placed on the other side to locate the ray as shown.

The problem with this method is that the curved surface of the block distorts (magnifies) the pins. To avoid this the two pins have to be close to the block thus limiting accuracy.

The advantage as I see it is that the arrangement is fairly easy to understand and relate to the theory because refraction only occurs at one boundary. After drawing in the rays the angles of incidence and refraction are easily measured. With care I was able to get satisfactory results.

I believe that sometimes the details of an experiment can confuse and distract students who cannot easily relate it to theory and hindering learning. One example of this I can remember from my student days is the method of mixtures for finding specific heat capacity.

Competition for Pluto

See my other blog for a post about Pluto.

Progress with superconductors

Superconductors are materials which have zero resistance and can therefore carry high currents with no energy loss due to heating. At present such materials only superconduct at low temperatures requiring cooling.

This is a quote from a report about the progress being made to use such materials in electrical generators as used in power stations. Any small increase in efficiency saves a lot of energy and money. There are references to several Physics concepts including electrical power and efficiency, temperature, heating, centrifugal force as well as superconductivity. Although not yet in the syllabus the term "superconductivity" is becoming important enough that any educated citizen should know what it means.

"The experts from Corporate Technology — the central research organization at Siemens — have acquired a great deal of experience with regard to electric motors and generators whose coils are made from high-temperature superconductors. These superconductors have an operating temperature of around minus 240 degrees Celsius. The electric current density possible with such windings is approximately 30 to 100 times greater than the values achievable with copper coils at room temperature. Following tests on a 400-kilowatt model motor, a four-megawatt (MW) generator operating at 3,600 rpm was subjected to a program of long-term tests. This was followed by tests on a 4 MW high-torque motor at 120 rpm. Each of these projects showed that the high-temperature superconductor technology halved the machines’ losses while also reducing their size and weight. "

Calibrating a thermometer

We recently did a standard calibration exercise using melting ice and boiling water. We calibrated some alcohol-in-glass thermometers which had broken threads. Some things we learnt:

• make sure the thermometer is in good contact with the ice (well crushed ice is best)
• there is a small difference between the temperature of the steam and that of the boiling water
• the thermometers with the broken threads were several degrees in error for both fixed points

It was a useful activity and also teaches that instruments do not always give correct readings!