Negative Resistance

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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Aircraft insulation

I read in the NZ Herald this week that one of Air New Zealand’s energy-saving strategies was to make sure an aircraft’s insulation is dry. Apparantly, 200 kg of water can be sucked out of a plane’s insulation.  Sounds impressive. The article appeared to be pushing the weight saving as the main cost saving. Two hundred […]

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Sticky Milk Powder

Earlier this week, we had the end-of-year display of student engineering projects. There were lots of posters put up to browse around over tea, several interesting large objects such as pieces of electric cars, and many fascinating talks given by the students. One of the most enjoyable talks was given by student Timothy Walmsley, concerning a study on […]

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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 […]

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Infra-red and heat

Here’s a bit of physics that’s coming up in my lectures – what’s the connection between heat and infra-red?  You’ve probably seen imagery from ‘thermal imagers’ or infra-red (IR) cameras, usually on police shows, taken from a helicopter as it follows a suspect fleeing down some alley-way at night.  You’ll see that ‘hot’ things (like […]

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It’s cold outside…

…Well, it was this morning. Those unfortunate people like us who have two cars and a lot of stuff and only a double garage, meaning one car has to sit uncovered on the drive, will have noticed that the ice on the car windscreen is generally thicker than the ice on the side windows. Why is […]

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Why you need to proof read

I’ve just supervised a test for a group of second year students. On looking at their answers afterwards, it was rapidly clear that there was a problem with one of the questions. Specifically, I had given the value of Boltzmann’s constant as 1.38 times 10 to the power 23  Joules per Kelvin, instead of 1.38 […]

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What goes up… must come down

Yesterday morning while driving into work I was reminded that this week is ‘Balloons over Waikato‘ – the annual hot air balloon festival.  It was hard to miss; I counted 20 balloons making their way gracefully over south-east Hamilton and drifting slowly towards Morrinsville. (NB: I counted the balloons AFTER I had parked the car, […]

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Mobile phone physics

Just occasionally, I have a crazy thought regarding a physics demonstration.   This is one that I’m thinking about inflicting on my third year electromagnetism class.   We’ve been discussing the way electromagnetic waves travel (or rather, do not travel) through electrical conductors. Basically, conductors allow electric currents to flow in response to an applied electric field (in simple terms […]

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