Science

Practical Science in u3a

Photo: A recent botany workshop done by the Practical Science group.

There are many active science discussion groups throughout u3a so it is perhaps surprising there has been relatively little in the way of complimentary practical science work.

This does seem a shame when there so many members who as children were keen to explore the sciences but were unable to continue their interest through lack of educational opportunity.

Conversely ,there also are many with extensive scientific experience who have worked only within the narrow confines of their chosen specialty but now in retirement wish to explore different areas of knowledge .

An early problem we experienced was that ideas and expectations between these two groups varied greatly . To help resolve this issue and to keep the group together we tried to run various projects in tandem to suit the needs of different group members.

We felt that the easiest starting point was probably in the area of Biological science, such as ecology and natural history which is most suited to group work and those exploring science for the first time .

Those members who had greater knowledge and experience in scientific areas often in IT and electronics, tended to favour doing their own projects at home and then presenting their work to the group.

We were also very lucky that our local college of education kindly agreed to provide access to their three science laboratories for group activities at no cost to us along with providing educational support with health and safety advice.

Biology and Natural History

One of the most popular activities has been mothing using an ultraviolet trap. A member sets it up overnight in their garden and then everyone meets up for a coffee to open the trap and identify the contents. We usually get around 50 moths of which we can identify about 15 species using the excellent ‘Field guide to Moths ‘ by Waring and Townsend. Most excitement comes from finding the spectacular giant hawk moths which are present in most gardens but which we normally never see. After identification the sleeping moths are carefully released under a bush away from predatory birds.

Another favoured activity is identifying common plants and butterflies in the countryside. This usually consists of a mornings visit to a particular habitat such as a woodland walk or stroll over local heathland.

A very successful laboratory project suitable for group work is wet microscopy looking at common protozoa found in ditches and pondwater. Alternative sources of material are simple hay infusions or alternatively pure species culture are available from standard biological suppliers such Blades Biological who provide organisms such as amoeba, paramecium and hydra.

Now that Spring is here we are looking at the lifecycles of solitary bees and dragonflies. A very easy group project is drilling 6-8mm holes in wood on south facing walls to provide homes for solitary bees.

Physics and electronics

One of the most interesting projects was initiated by Mike who built a cloud chamber to detect cosmic radiation. As the radiation passes through a saturated vapour it momentarily condenses in a white streak rather like the receding vapour trial of a jet across a clear sky.

The beauty of this simple device is that it can be build with items from your average kitchen. We chilled our chamber with solid carbon dioxide.

We all met in the physics laboratory at Chichester College and various designs of cloud chamber were tested. Most exciting of all we had access to a wide variety of radiation sources from radon gas and thorium oxide which generated alpha particles to strontium 90 which emitted beta particles which could be bent by applying a powerful magnet. On insertion of the radioactive source into the cloud chamber a steady stream of particle vapour trails was easily visible.

Another member had an interest in the historical development of early electric motors and detailed the surprisingly complex modification developed in the Victorian era to improve performance. A complimentary practical session was held at Chichester College to assemble simple motors driven by a 3v battery.

More experienced members are in the process of launching a 3D printing project.

Chemistry and Kitchen Science

A variety of projects have been undertaken over the year including the steam distillation of lavender flower to isolate the aromatic oil . Yields were disappointingly low but the house smelt nice for days.
With the interest in hydrogen cells and green energy some work on factors affecting on simple electrolysis of water using a Hoffmans voltammeter were undertaken.

Visual chemistry is a popular option with one coffee morning demonstrating oscillating reactions using the iodine clock reaction and the famous dynamic reversible BZ reaction which produces wonderful patterned waves that stream across a petri dish.

A woman with a bucket holding up pieces of paper

Various forms of chromatography have also been popular starting with paper chromatography using coffee filter paper and coloured pens with water or ethanol as an eluent depending on the type of ink. (Photo above.) Later experiments used TLC plates to identify complex organic compound . The final phase of the project involved individual separation of isomers using solid phase chromatography in columns of silicon dioxide.

In the warmer weather of last summer Jeremy had great fun last year producing a variety of tasty ice creams with liquid nitrogen.

One of the most stunning experiments last year was applying a vacuum to liquid nitrogen forcing it to boil under reduced pressure so that it froze at minus 210 degrees centigrade!

Next years big project is to look at quantum levitation using low temperature superconductors chilled with liquid nitrogen.

If there are any other science groups who wish to collaborate and exchange ideas on practical projects please do get in touch with Chichester Practical Science Group through our website.