Renewable electricity??

I know what we mean by a renewable energy resource but I'm struggling with the idea that electricity is renewable. Assuming it keeps raining (a fair bet in the Scottish Highlands) then Lochan na Lairige will continue to be refilled with water. That's renewable. The water flows down the pipe below the dam from an altitude of 500 metres down to a power station on Loch Tay over 300 metres below. The gravitational potential energy turns into kinetic to drive a turbine and generate electricity. I teach that renewable means "won't run out". The gravitational potential in the water at the top of the hill will continue in perpetuity. So can we say that the electricity itself, as the end product, is renewable or should the sign say "electricity generated from a renewable energy source"??

St Albans

We had a great time ringing bells in St Albans but I didn't find much Physics. The bell tower at the Cathedral was very high up giving amazing views, so there is the Physics teacher's fall back of lightning conductors. If you magnify the image you'll see that they are copper due to the green colouration when corroded. I did like the notice in the second picture.

New College Oxford

New College Oxford is not new. In fact, it is one of the oldest colleges. It is now best known for this tree which appeared in one of the Harry Potter films. I was more taken by the giant sundial. The notice says that it was put in for the Millennium. It also explains why it does not show GMT and explains how to convert to GMT.

Absorption spectrum for the Sun

The boss found some old spectroscopes on Friday afternoon. The small ones turned out to be the best. I have never seen the absorption spectrum of the Sun with my own eyes before. Here it is! You can clearly see the black lines where hydrogen atoms in the colder (on 4000C ish!) chromosphere have absorbed photons of light and re-emitted them randomly, reducing the intensity. I'm ecstatic.

Ashmolean museum

I went round the Ashmolean Museum in Oxford last month. It's just reopened after a major refit. I was amazed by the amount of Physics. Here's a piece about radioactive carbon dating!

Spectra on the windows

One of my colleagues inspired me to use colour films on my windows. It's such a brilliant idea and I can't understand why it hadn't occured to me before. Seven colours in the spectrum is a contentious idea. It is alleged that Sir Isaac Newton chose 7 as being the perfect number. He was into odd things - he was an alchemist in his spare time, I believe. So my 6 colours are not in fact wrong!

Bluebeard

Thanks to all of you who sponsored me to have my beard dyed blue in aid of Practical Action. This charity was called Intermediate Technology and was supported in the 1980s by some of my heroes. It works to use sensible technology to make life better for poor people in remote places. As such, it is a good outworking of Physics principles. I'm raising money for solar powered wells.
The dye experiment has been problematic. We put on three lots of dye but I was left with a pale turquoise "blue rinse". Beard hair is too strong. I've been told that peroxide bleaching would break up the hair allowing it to absorb more dye. I've tried the chemists but you can't buy it any more following high profile bomb plots. However I have learned a lot about Chemistry in the process. I'll keep you posted...