Blue light on the coral

At the aquarium we were shown blue light shining onto the coral. 

Apparently this coral obtains most of its energy by having a symbiosis with a unicellular organism which does photosynthesis, hence the need for light. I asked about why blue light. I was told that the photosynthesis would work in white light but that the blue light is used so that the green colour is very clear. There was ambient white light from the room as well that gets in through the front of the tank. Perhaps it is the reflection of part of this that I was seeing in the green colour because in colour theory, surely shining blue onto green should look black. Or else the blue covered a vast slab of wavelengths that included green.

Lots of Teslas

I used to park in the car park near this research facility and was always happy to see the signs warning about high magnetic fields. The unit for magnetic field strength is the Tesla. I suppose these days younger students will think it's named after the cars. Teslas always seemed like a mis-sized unit. So one of the strongest magnets there is has reached 11.7 Teslas. It's like capacitance in that most values you come across are milli and micro.

Lunar New Year

I was intrigued by this card. I was wondering how you would decide when to start a year in a lunar calendar. If you follow a strictly lunar calendar, then the months don't tie in with the solar calendar we use. So Ramadan occurs in different western seasons as the years go by. The answer to this Lunar New Year is that it is not truly lunar. It is called a lunisolar calendar where a "leap month" is put in every now and then to make the same festivals come up at the same point relative to the sun every year. This is called intercalation.

Nannycatch

The Nannycatch Valley is an impressive, steep sided gorge. I have read that it was formed at the end of the Ice Age when glacial meltwater was dammed. When it burst through, the wild surge of water carved the valley. I can't find a reference to it on the Internet amid the walking routes. It must have been in a book so I need to search out that reference. The force of the water must have been immense.

Work done to put a stone on Dent

This stone on Dent is obviously a glacial erratic and lots like the Ennerdale Granophyre. You can see the origin in the distance up to 10km away. My poles are 1.4m long so the stone is approximately 1m x 1m x 0.5m = 0.5 cubic metres. The rock gas a density of say 3000 kg/m^3 to 1sf. Mass of rock = 1500kg. Weight of rock = approx 15000N. Now if I wanted to calculate the work done by the glacier moving the stone 10km, which force would I use? Could I say that the work has been done against gravity holding the stone up? Or is it work done against friction? And if so, is that friction under the stone, which might be held fast anyway, or friction under the glacier? Can't resolve this at the moment.

You've got potential

 

Potential is such a wonderful physics word. I used to say that if I wrote on a report "this student has potential" then it wasn't a good thing. It would mean you'd got the ability but weren't using it.

Interesting diffraction rainbow

I noticed the rainbow to the right of the mug. It is not correct for a CD reflection grating which should be a radial pattern.

Then I edged the mug round a bit and realised it was diffracting the light reflected from the curved white mug handle.

Old Watendlath hydro part 2

The drive shaft has been cut.

It runs through a fly wheel to a grooved disc on the end. I'm guessing that had drive belts which then drove a generator that was out of line with the turbine.

Old Watendlath hydro part 1

This machinery is in the corner of the car park at Watendlath. According to this article, it is a hydroelectric plant from the 1920s. It looks like the water must flow into the top pipe. I guess there is some kind of Pelton Wheel in the spiral beneath and that the water then flows out of the middle and then down.

USB hand warmers

I saw these in a shop.

10000mAh for 13.5 hours means a current of 0.74A. USB voltage of 5V would give a power of 5 x 0.74 = 3.7 Watts.

Here current is 5200mAh / 8 hours = 0.65A. That would give a power of 3.25 Watts. Not sure if these are valid calculations because of the voltage but 3W in an enclosed glove will have some effect.

Carbon negative

I keep seeing the phrase "carbon negative" but mostly on the side of wood lorries when I'm driving and can't photograph it. I was wondering if the process was sucking carbon dioxide out of the air but it means that the company is in a scheme to plant trees that more than offset the carbon dioxide released in the processes of producing and distributing the product.

Light tubes

These shoes are displayed on clear plastic pegs. There seem to be pin LED lights in the holes. They travel straight through the plastic and light up the end. You can see that very little light has escaped from the sides. It's acting as a wave guide or an optical  fibre. What doesn't matter is the fact that the light goes slower in glass because the light doesn't change direction if it goes straight. 

Light travels in straight lines

As shown by the amazing light show in Carlisle. Well, I suppose it shows that space-time is flat here because if it were curved, light would follow that surface. 

Over precise!

This is data for a car loaded automatically by a booking website.

So the length of the car is to the nearest meter which seemed appropriate in the context. But height and width to the nearest mm seems over precise. 1.5m would be better IMHO! 

Wave reflections in Blackpool

The reflection of plane wavefronts was obvious on Blackpool Promenade. 

More 0.0%

This can is more explicit about the reason for it being 0.0% rather than 0%. It does mean what I thought it would.

Within tolerance?

You would never have got away with giving a measured amount +- a % in an exam. That's partly about units but probably had a lot to do with the extra calculation needed to turn the percentage into a value. 8% of 620 grams is 49.6 grams, so this is 620 +- 50 grams. The reading below shows that the cardboard box is too heavy.

Units for air pressure

I have inherited a barometer than only has units of inches. I was wondering what that meant and how to link it to the Internet readings in millibars. Then I found this one that has both scales. I think that inches refers to a mercury barometer, where the air pressure supports a column of mercury. These days, the units are usually given as mmHg. Now I can see that 1000millibars would support a column of mercury that just over 29.5 inches high.

When is 0% not 0%

I've been noticing that no-alcohol beers are given as 0.0% alcohol rather than just 0%. Perhaps it's to do with the way decimal places are used to show precision. If we've decided on no decimal places, then 0.4% would round down to 0%. I'm sure the made-for-kids shandy cans in the 70s were around 0,4%. By claiming 0.0%, you can be sure there's basically no alcohol present.

Siddick Wind Farm

 

This is an old wind farm, dating from 1995. It is well sited on the coast. It's name-plate capacity is 4.2MW which is not quite as high at St Helens Solar Farm across the road. It could power half of Wigton

Super sunset

This was the sunset on Thursday night in Woodstock. I wasn't the only person out photographing it. Then I found this article. Woodstock is about as far from the sea as you can get in the UK. If salt was enhancing the sunset colours it would be impressive.

Good example of the need for an earth connection

These old-fashioned radiant heaters are regarded as dangerous these days. The modern convection heaters are much safer. Once I used to use these as a good example of the need for an earth connection. The case has to be made of metal so that it doesn't melt. However if the live connection comes lose and touches the outer case, you would complete the circuit to earth if you touched the case and would get a nasty shock. So the earth wire is soldered to the case. If the live wire comes lose and touches the case, the current follows the route down to earth. It is a low resistance route so the current is high enough to blow the fuse and make the device safe.

Microwaving my soup

I had no idea how long to set the microwave for my soup so I did it in short bursts to avoid an accident. I realised later I could do a rough calculation. I used half of 600g container, so mass is 0.3kg. Let's assume it's water. From fridge to boiling is 95oC temperature change. Energy = m. c. Delta Theta = 0.3 x 4200 x 95 = 120000J to 2sf. I used 900 Watts so 900 Joules per second. Time would be around 2. 25 minutes. But allow for heating the bowl and unknown efficiency then 3 mins would be a decent starting point next time.