Mercury maximum elongation

My book told me to get out at 7.30pm to see Mercury. The arrow shows Jupiter. Mercury was in the circle but the sky was to bright there for it to stand out in the photo. It has led me to find out what elongation means. It turns out that it refers to an angle. It is the biggest angle between the Sun and the planet as seen from Earth, so I suppose it must make it seem furthest from the Sun and in Mercury's case, makes it easier to see.

Testing the bin lid

I realised I have a dB meter on my phone. The bin is rated 89dB so not far off but my conversation was this loud! 

Comparing electricity supply sources

 It must be mandatory now to show sources on bills. Here are a couple I've been shown:

The second makes a point of being 100% renewables.

The bottom of a lightning conductor

 

I noticed that the lightning conductor was double thickness at the bottom - made of two parallel strips. I wondered if that was a standard feature but I haven't been able to find anything. However I did find this brilliant article. I hadn't considered what happens below the ground. So the system needs to take the current away from the building. In this case I'd hope towards the graveyard because directly away from the building was towards a house a few metres away! 

Glow sticks

There were glow sticks at Laura's party! I've always known that flexing the case breaks a chemical container inside allowing two chemicals to mix. Looking up the details here has got me doing some thinking. It says that the reaction is exergonic. This seems to be because the reaction is at constant temperature. The graph seems similar to the one I taught for exothermic reactions but they would release heat and presumably the temperature wouldn't remain constant. The energy released seems to excite a dye compound, meaning that the electrons go up energy levels. They de-excite by releasing a photon and if the dye is chosen so that the energy levels produce photons that lie in the visible range, we have a glow stick. Would we still call them glow sticks if there were photons released but not visible to the human eye?

Sensing the temperature

There is a brass-coloured cylindrical piece of metal clipped to the back of the heater. It is then attached to the thermostat control by a long bare piece of wire.

Somehow this must be sensing the temperature behind the heater. The mechanism sounds like a bimetallic strip kind of sensor. Perhaps the long metal wire is conducting heat here not electricity!

Increasing the surface area

This electric wall heater has two heating elements. The device has a switch that toggles between "half" and "full" ie one element connected or both. There are thin metal plates that sit perpendicular to both, with the elements going through them. These are to increase the surface area. The idea is that when the air touches the hot metal, there is transfer of thermal energy by conduction. The more metal that is touching the air, the more of this can happen at once and the faster the air heats up. The air expands, becomes less dense and rises. This allows colder air from below to move in to touch the plates.