Youtube films I really like

Here they are again
Bohemian Gravity for string theory
https://www.google.co.uk/webhp?sourceid=chrome-instant&rlz=1C1EODB_enGB572GB574&ion=1&espv=2&ie=UTF-8#q=bohemian%20gravity

Smarter Every Day and Veritasium do the Coriolis Effect
http://www.smartereveryday.com/toiletswirl/

Spark counter for alpha radiation

It was out with the spark counter again. Nearly 3000V between the thin wires at the front and the backing plate. That is not quite enough for the air to conduct electricity. The alpha particles are helium nuclei so they have enough momentum to dislodge electrons from air atoms, turning them into ions. These charged particles can conduct electricity so you can see sparks when the alpha is present. It is ionising radiation.

D of E navigation nightmare

We were out with the Silver Duke of Edinburgh's Award walkers when we noticed this potential compass problem. If you hold the compass next to an iron gate, you can get the wrong direction for North. The compass needle is a magnet. It's magnetic field is strong enough to line up the domains in the iron, turning it into an induced magnet, which attracts the compass needle. Hence the needle will always point towards the gate - giving the wrong direction for North.

Ultrasound: mouse and rat repeller

I love the definition of ultrasound: any frequency above the highest that a human can hear. The highest we can hear is 20000Hz. This unit sweeps from 30000 up to 60000Hz. This is important because cats and dogs can hear up to 27000Hz so they are not distressed by the device. The garage is an ideal location for it because the hard wall surfaces reflect the sound round the space so one unit can cover the entire room.

How good is the night sky?

The square of Pegasus is a familiar landmark in the night sky at the moment, They say that you can judge how good the viewing conditions are by how many stars are visible in the square. I can see about half a dozen on a good night in Wigton. There is the added problem of how ours eyes work. They rod cells round the outside are better light detectors than the cone cells in the middle of the eye. So I can sense more stars inside the square but as soon as I look directly at them, the cone cells take over and the stars disappear because they are too dim to be detected by cone cells.

Lux in Wigton

We were intrigued by the name of the new tanning salon in Wigton. Lux is the SI unit for light received, as perceived by the human eye. It's a measure of the intensity of the light in Watts per square metre but factored to account for the fact that human eyes perceive some wavelengths as more intense than others. Hence the same Watts per square metre in yellow would have a higher value in lux than red. Now the name of the salon might be short for luxury but since sunlight for suntans could be measured in lux, I think it's an awesome name.

Winglets at Newcastle Airport

I noticed that our aeroplane had upturned wingtips. These are called winglets and are used to reduce the vortices that are formed at the tips of the wings. You can see these vortices in certain atmospheric conditions. There is a pressure difference between the air masses below and above the wing and this difference cause mini-hurricanes. Looking up this topic reveals the drag factors on aeroplanes to be very complicated so more research needed.