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Science, Maths & Technology

Kathy's Carriacou diary: Sun & sea

Updated Monday 28th January 2008

Kathy Sykes's Sun and Sea diary, from the BBC/OU series Rough Science 2

Day 1

Incredulous - Kate wants me and Mike B to make an underwater torch. A torch that works above water would be hard enough!

J, Ellen and Mike L are topping up the car battery (for the torch) with distilled water and also recharging it. Wow!

Mike B and I talked about how we'd do it:

Possible physics solution: a light bulb
Possible chemical solution: make phosphorus
Possible biological solution: fireflies (!)

Mike B said phosphorus making is dead hard - and he wasn't convinced it would work. So we both had to use our own approaches to make sure one thing did work. Mike B began collecting, bashing, grinding and boiling bones. I just think it's amazing how little we can know about each others' subjects. I thought chemistry was pretty close to physics but I'd be CLUELESS about making phosphorus. Mike B claimed to be clueless about circuits and wiring things. Couldn't quite believe him (it's too easy to assume that what you find easy - other people will also find easy).

I tried out lots of different filaments - all the wires that didn't have insulation (and weren't copper - it conducts too well); and also carbonised (burned) hair and paper. Thankfully - had some fab stuff that glowed wonderfully when about 5 coils long. Hurrah!! The problem was it glowed best at shorter lengths but then burned through. Needed to get low pressure inside the jar and remove the oxygen so it can't burn.

Explained voltage, current and resistance to Kate. V chuffed - she was so excited to understand it for the first time.

Meanwhile - Jonathan built an even bigger and lovelier contraption to turn the parabolic mirror to face the sun. At end of day I was ready to try out an experiment: comparing my 'bulb' (emptied of oxygen by burning a candle in it) in a filament open to the atmosphere. Expected jamjar bulb to last longer. Spectacular failure! Really funny! Probably 'cos I didn't measure filament lengths exactly (measured 4 coils instead of cm). That'll teach me to be sloppy!

Fun day working with Mike B - who's hysterical and the '18-30' film crew. Laughed our way through the day!


Day 2

Decided to stop messing about with resistors and just put the whole 12V across the filament. I want as much power as I can get.

So I had to try out different lengths of filament until I found one that just wouldn't burn out (since the shorter the filament - the brighter it burns).

Repeated yesterday's experiment with 12cm, 11cm, 10cm, 9cm, 8cm and this time, with more accurate measurement of filament length it worked!

Then messed around with Ellen's sealant trying to get a decent seal, that would not only keep jamjar at low pressure but would also keep water out. Left sealant on to harden in the sun and went to do snorkelling scenes with Mike B. Sarah persuaded us to walk from lime factory to the sea in our fins. Just mad and ridiculous. Would really rather not have my thighs exposed on national TV but it would look so funny - it had to be done. I really believe science programmes need more humour (tho' some question marks about making scientists look insane!)

End of day, dusk scene of me trying out my bulb underwater. Not confident at all. But it worked. Yipee! So lucky to have so many end-of-day successes.


Day 3

Fantastic end of day success!

Last night Mike B had to stay late at the lime factory - tending to his phosphorous. So a load of us (his team basically) stayed too: Sarah, Drew, Paul, Kate, Angie and I working in at the silhouettes in flickering candle-light.

It was wondrous! We sat around candles munching pizza, swigging beer, smokers smoking for Britain - and told ghost stories. Paul had some fab stories. Sarah and Kate had great stories of ghost-sightings. Scared ourselves senseless!

Thought today would be straightforward. Not much to do. Just making a back-up torch; devising a way to hold it off the sea floor, but below the sea - and building a duplicate in case it failed. But - of course - ended up being a mad panic again.

Began day with huge disappointment though. Mike B's arduously nurtured phosphorus - was not phosphorus. It was such a hard thing to try especially when we have no control over the temperature of the furnace. Poor Mike B - he really deserves a huge success. And however 'big' and mature he is - it's so disappointing not to get a big 'wow' when you deserve one.

Had to finish at 3 pm to get to the dive centre to get the boat to test out if the light bulb would work underwater.

Huge safety talks - a car battery on a boat, a boat needing 5 scientists (and camera crew) - and no boat handler in sight. A director who's scuba diving. Quite, quite mad.

Then had to kill an hour - waiting for sun to lower (and not fry us all up in the boat). So frustrating to have had to rush so much to get ready - then sit about and wait.

All pretty tense in boat - trying to catch sunset and shots above and below water - to me a little precious that, if my bulb worked at all - it MAY only work once (could the sealant possibly work at the high pressures the water would be at!).

The product team seemed to think this was trivial. Do they have a huge amount of confidence in my bulb? Or are they just too busy worrying about their own issues? (NB - Discovered that this was one of the few challenges they DIDN'T try out - and a couple of people had said 'it won't work'.)

Anyway - it was fine. The bulb DID glow underwater - so much so that we could see an inquisitive fish coming to study it. Very funny.

And that moment when we lowered it in - and it didn't bubble - felt just fantastic. Get goose pimples just remembering it. Just wish these moments happened so regularly in real research!


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