I was having a conversation last week with a student about negative resistances (in an electronics context). These are just as they sound – to send a current from terminal A to terminal B you have to apply a higher potential to terminal B than terminal A. Sounds backwards? Yes – it is. That’s why […]
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Cold and humid
Saturday was one of those days that the Waikato winter is famous for. Cold and damp – by damp I mean humid as well as raining – in fact the kind of weather that reminds you that you are living in an area that used to be one massive swamp. The sort of dampness that […]
Continue readingPeak Oil, peak platinum, peak physics
I guess most of us now are familiar with the concept of Peak Oil. At some point (maybe about now) oil production will peak, then it will be in decline as reserves run out. The only way around this issue is to reduce our use of it, which means, for example, reconsider our transport options. […]
Continue readingIt never works when you need it to
A couple of weeks ago my wife mistook an old glass jug of ours for a pyrex one and poured boiling water in it. The result was quite pretty, with a jigsaw of cracks across the jug rendering it incapable of holding any fluid ever again, boiling or otherwise. That’s thermal expansion for you. Glass […]
Continue readingHeads I win, tails you lose
The comment on my previous entry raises a few issues with the way we feel heat. (NB for those who normally read this blog on http://www.sciblogs.co.nz , you’ll need to go onto physicsstop to see the comment – https://sci.waikato.ac.nz/physicsstop ) How hot we feel has more to do than just what the temperature is. Anyone who […]
Continue readingBBQ Physics
Here’s another little bit of physics seen in everyday stuff. When disconnecting the gas cylinder to our camp stove while on holiday, I got a bit of a shock at how cold it was. It shouldn’t have shocked me – that’s how it should be. When gas is made to expand it cools down. And in […]
Continue readingClimate change
I feel that, as a physicist, I should be making some reasonable and informed comment on the Copenhagen summit. After all, climate is immensely physicsy. We have fluid flow, conduction, convection and radiation of heat, interaction of electromagnetic radiation with electrons in molecules, scattering of light by small particles, solar activity (on second thoughts, scrub […]
Continue readingRisky things
I love the headline at the end of last week ‘Wellington quake risk halves’. As if you can wake up one morning and find that the chances of an earthquake happening today are suddenly half of what they were yesterday just because someone says so. What next – someone decreeing that summer will last 12 […]
Continue readingThe end of the week…
Have you ever had one of those days when you have worked flat out all day and seem to have accomplished nothing? I think that’s today. My desk looks like a tornado has been through the office. Now, I wonder, statsitically speaking, how many tornados I’d need to come through before one picked up all […]
Continue readingBiology and the second law of thermodynamics
At my recent conference, one of the speakers (Karl Friston) began by remarking on the curious relationship between biological systems and the second law of thermodynamics. What is curious about it, is that there doesn’t appear to be one. As any physicist knows, the second law of thermodynamics is inescapable – things break, electronic equipment […]
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