What Does Sound Look Like?"When light passes between areas of different air density, it bends.You’ve probably noticed the way distant pavement seems to shimmer on a hot day, or the way stars appear to twinkle. You’re seeing light that has been distorted it passes through varying air densities, which are in turn created by varying temperatures and pressures.In the mid-nineteenth century, German physicist August Toepler invented a photography technique called Schlieren Flow Visualization to visually capture these changes in density.”Learn more from NPR.
Plasma ball demonstrations Part II
Top row: Helium, krypton, and neon noble gases are ionized in their glass tubes. The plasma globe’s strong electric field rips the electrons off their atoms and as they return to their various orbitals (levels around an atom) they give off light in that element’s characteristic spectrum.
Bottom row: The plasma ball provides a safe source of high voltage that allows the use of cathode ray tubes (you can also find them in a plasma television screen) to explore how electrons are deflected by magnetic fields.
This one of the things I love about physics. A wave is always a wave. Always governed by the same rules, whether it’s a light wave, or a sound wave or a water wave (but probably not a Mexican wave)
Here there’s a speaker set to emit a frequency of 24Hz. That means that the speaker is going to vibrate 24 times in one second. So it causes the water stream taped to it to shake 24 times a second.
Then there’s a camera that takes 24 images a second, and since that’s how often the water shakes. it looks like a freezed image. Of water boogieying down.
I work with waves a lot so this stuff is crack to me.
In case you missed it
This is really cool. At the science museum near my house, this is possible in real time, by synchronizing a strobe light with the frequency of the sound wave. This gives the illusion of the camera with the 24 fps, and making it seem to stand still.
Yep, and it is really trippy to watch. They did it in the Science Gallery below where I work. Gave me a head ache after a little while. I heard once that pigeons see at a higher frequency than 24Hz so to them a movie would seem like a series of still slides.
Newton’s third law says that forces come in equal and opposite pairs. This means that when air exerts lift on an airplane, the airplane also exerts a downward force on the air. This is clear in the image above, which shows a an A380 prototype launched through a wall of smoke. When the model passes, air is pushed downward. The finite size of the wings also generates dramatic wingtip vortices. The high pressure air on the underside of the wings tries to slip around the wingtip to the upper surface, where the local pressure is low. This generates the spiraling vortices, which can be a significant hazard to other nearby aircraft. They are also detrimental to the airplane’s lift because they reduce the downwash of air. Most commercial aircraft today mitigate these effects using winglets which weaken the vortices’ effects. (Image credit: Nat. Geo./BBC2)
Demonstrations with Plasma balls: Part I
Top row: Investigate the Electrical field
'Using an oscilloscope determine how the voltage decreases with radial distance by moving the probe in and out. You can also use speakers to hear the frequencies. The human body can serve as an excellent antenna so be sure to touch the end of the cable’s tip.’
Second row: Fluorescent tubes
'You will notice that when part of the mercury gas starts glowing in the tube it can stay glowing even as you extend it. There is essentially no limit to how far you can pull the tube. At certain distances however the tube will not glow to begin with. There is a minimum electric field required to ionize the mercury gas - and it the field is not strong enough the tube will not light.
Bottom: The path of least resistance
The electric field can be diverted to a grounded shorter circuit if you grab part of the tube.
I’m skeptical - surely there’s a limit to how far you can pull it… I mean if you had an infinitely long fluorescent tube?