The crafty chemist

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Posts tagged with "physics"

Oct 7

ri-science:

A cloud chamber and the birth of helium atoms.

The tracks here show the natural radiation in the atmosphere around us. Thicker tracks are big heavy alpha particles, whispy ones are beta particles, but they all work in the same way.

The atmosphere in the chamber contains a lot of alcohol vapour. When charged particles fire through the atmosphere they cause little droplets to form, and these are the clouds you can see.

This is similar to how a track forms behind an aeroplane, where the exhaust can help the droplets of moisture form together into a cloud.

When you then add an Americium pole into the chamber, the alpha particles emitted (with their two protons and two neutrons) grab electrons and form Helium atoms. 

Watch the full video with Dr Peter Wothers on YouTube.

Oct 6

bluedogeyes:

The Higgs Boson Re-Explained (via PHD Comics)

Oct 5
nanodash:

This is William Herschel’s prism. In 1800 he passed sunlight through it and noticed that past the red end got hotter than the visible section.
He decided there had to be another kind of radiation which he called “Calorific Rays.” Which we now call infra-red rays. A little piece of awesome history.
Herschel was an absolute screaming genius though, he discovered Uranus,  and some of Saturn’s moons. He proved coral wasn’t a plant showing that it didn’t have cell walls and wrote a buttload of symphonies.
Oh, and he coined the word “asteroid.”

nanodash:

This is William Herschel’s prism. In 1800 he passed sunlight through it and noticed that past the red end got hotter than the visible section.

He decided there had to be another kind of radiation which he called “Calorific Rays.” Which we now call infra-red rays. A little piece of awesome history.

Herschel was an absolute screaming genius though, he discovered Uranus,  and some of Saturn’s moons. He proved coral wasn’t a plant showing that it didn’t have cell walls and wrote a buttload of symphonies.

Oh, and he coined the word “asteroid.”

Oct 4
skunkbear:

At 10:02 AM on August 27th, 1883, a volcanic island in modern day Indonesia called Krakatoa erupted. The blast sent shockwaves across the ocean, triggering tsunamis that destroyed the coast of Java and Sumatra. The sound was so loud it was heard 3000 miles away.
As Aatish Bhatia notes in this recent article: “What we’re talking about here is like being in Boston and clearly hearing a noise coming from Dublin, Ireland." 
Barometric readings at the time clocked the sound pressure at 172 decibels ONE HUNDRED MILES AWAY from the island.
Here’s a handy reference:
Using a jackhammer — 100 decibels
Human threshold for pain — 130 dB
Standing next to a jet engine — 150 dB
And the scale is logarithmic - so a 10 dB increase doubles the loudness.

skunkbear:

At 10:02 AM on August 27th, 1883, a volcanic island in modern day Indonesia called Krakatoa erupted. The blast sent shockwaves across the ocean, triggering tsunamis that destroyed the coast of Java and Sumatra. The sound was so loud it was heard 3000 miles away.

As Aatish Bhatia notes in this recent article:What we’re talking about here is like being in Boston and clearly hearing a noise coming from Dublin, Ireland."

Barometric readings at the time clocked the sound pressure at 172 decibels ONE HUNDRED MILES AWAY from the island.

Here’s a handy reference:

  • Using a jackhammer — 100 decibels
  • Human threshold for pain — 130 dB
  • Standing next to a jet engine — 150 dB

And the scale is logarithmic - so a 10 dB increase doubles the loudness.

that-angle-of-refraction-though:

The movement of a single particle in an Ocean wave

I always think of waves as a sine curve, but it’s actually called a trochoid, the shape you get it you mark a point on a circle and roll it forwards.

GIF video source

that-angle-of-refraction-though:

The movement of a single particle in an Ocean wave

I always think of waves as a sine curve, but it’s actually called a trochoid, the shape you get it you mark a point on a circle and roll it forwards.

GIF video source

(Source: trigonometry-is-my-bitch)

thekidshouldseethis:

This Rube Goldberg machine is “powered” by a single beam of light, using mirrors, magnifying glasses, and reflective surfaces to burn through strings, melt ice, pop balloons, and more… 
Watch the video.

thekidshouldseethis:

This Rube Goldberg machine is “powered” by a single beam of light, using mirrors, magnifying glasses, and reflective surfaces to burn through strings, melt ice, pop balloons, and more… 

Watch the video.

Sep 9

The Weissenburg effect

In the above gif (clear liquid) a dilute (0.025 wt%) solution of a high molecular weight (2×106 g/mol) polystyrene polymer (Polysciences Inc) is dissolved in a low molecular weight (~100 g/mol) newtonian viscous (~30 Pa.s) solvent (Piccolastic, Hercules Inc).

In the experiment a rod is rotated with its end immersed in the fluid outlined above.  In the Newtonian case inertia would dominate and the fluid would move to the edges of the container,away from the rod. 

Here however the elastic forces generated by the rotation of the rod (and the consequent stretching of the polymer chainsin solution) result in a positive normal force - the fluid rises up the rod.  The bulbous shape remaining at the end of the video is the onset of instability as the mass that has been forced up the rod a) relaxes and b) overcomes the force pushing from below.

Source

Video source, GIF source

Sep 8
invaderxan:

A cardboard cut-out of a cat imaged by photons that never went through the cut-out itself. Physicists have devised a way to take pictures using light that has not interacted with the object being photographed.
[x]

This is just so weird:

The researchers imaged a cut-out of a cat, a few millimetres wide, as well as other shapes etched into silicon. The team probed the cat cut-out using a wavelength of light which they knew could not be detected by their camera. “That’s important, it’s the proof that it’s working,” says Zeilinger.

but that’s because:

One advantage of the technique is that the two photons need not be of the same energy, Zeilinger says, meaning that the light that touches the object can be of a different colour than the light that is detected. For example, a quantum imager could probe delicate biological samples by sending low-energy photons through them while building up the image using visible-range photons and a conventional camera. (The work is published in the 28 August issue of Nature1.)
Zeilinger and his colleagues based the technique on an idea first outlined in 1991, in which there are two paths down which a photon can travel. Each contains a crystal that turns the particle into a pair of entangled photons2, 3. But only one path contains the object to be imaged.
According to the laws of quantum physics, if no one detects which path a photon took, the particle effectively has taken both routes, and a photon pair is created in each path at once, says Gabriela Barreto Lemos, a physicist at Austrian Academy of Sciences and a co-author on the latest paper.
In the first path, one photon in the pair passes through the object to be imaged, and the other does not. The photon that passed through the object is then recombined with its other ‘possible self’ — which travelled down the second path and not through the object — and is thrown away. The remaining photon from the second path is also reunited with itself from the first path and directed towards a camera, where it is used to build the image, despite having never interacted with the object.

This is the strangest thing I’ve read all week.

invaderxan:

A cardboard cut-out of a cat imaged by photons that never went through the cut-out itself. Physicists have devised a way to take pictures using light that has not interacted with the object being photographed.

[x]

This is just so weird:

The researchers imaged a cut-out of a cat, a few millimetres wide, as well as other shapes etched into silicon. The team probed the cat cut-out using a wavelength of light which they knew could not be detected by their camera. “That’s important, it’s the proof that it’s working,” says Zeilinger.

but that’s because:

One advantage of the technique is that the two photons need not be of the same energy, Zeilinger says, meaning that the light that touches the object can be of a different colour than the light that is detected. For example, a quantum imager could probe delicate biological samples by sending low-energy photons through them while building up the image using visible-range photons and a conventional camera. (The work is published in the 28 August issue of Nature1.)

Zeilinger and his colleagues based the technique on an idea first outlined in 1991, in which there are two paths down which a photon can travel. Each contains a crystal that turns the particle into a pair of entangled photons2, 3. But only one path contains the object to be imaged.

According to the laws of quantum physics, if no one detects which path a photon took, the particle effectively has taken both routes, and a photon pair is created in each path at once, says Gabriela Barreto Lemos, a physicist at Austrian Academy of Sciences and a co-author on the latest paper.

In the first path, one photon in the pair passes through the object to be imaged, and the other does not. The photon that passed through the object is then recombined with its other ‘possible self’ — which travelled down the second path and not through the object — and is thrown away. The remaining photon from the second path is also reunited with itself from the first path and directed towards a camera, where it is used to build the image, despite having never interacted with the object.

This is the strangest thing I’ve read all week.

Sep 6

The Coanda effect

"So, one would expect the air to flow out of the fan horizontally in all directions, but due to the Coanda effect; the air bends down, to almost 90 degrees.

The airflow is being pushed down by the air above, because the pressure of the air in between the flow and the curved surface, is reduced by the suction of the airflow.

Air is being accelerated down, and part of the upper surface is in touch with reduced air pressure. This action gives the object a force up, thrust, that can lift the object.
Henri Coanda realized this, and then designed a flying disc based on this effect, in 1932!”

The Coanda effect, named after Romanian aerospace pioneer Henri Coanda is the basis of an experimental flying saucer which went into production in 1958. Albeit it couldn’t fly more than a couple of feet off the ground, but theoretically if it were lighter it should have been able to overcome the ground effect and fly. It was called the Avrocar; it wasn’t very practical however due to it’s instability, noise, and overheating problems - only two were ever produced before the program was disbanded by the US military. The design was thought to be the inspiration for the first hover craft.

Video source, Avrocar image source, Avrocar video

8bitfuture:

Worlds fastest camera shoots 4.4 trillion frames per second.
A Japanese team has created a recording device able to acquire 4.4 trillion images per second, at a 450 x 450 pixel resolution. The technique could be used to further research into heat conduction and chemical reactions, according to its creators.
If the resolution can be improved, it could also prove useful for manufacturing, where it could keep track of laser cuttings in real time.

The technique, known as a Sequentially Timed All-optical Mapping Photography, or STAMP for short, shuns the conventional methods employed by other superspeed cameras to achieve results up to 1,000 times faster than has been previously available. The current leading brand of high-speed real-time recording is a method unfortunately known as the pump-probe process, where light is “pumped” at the subject and then “probed” for absorption. STAMP differs from this by skipping the need to constantly probe, or measure, the scene to construct an image, instead it uses single-shot bursts to acquire images and maps the spatial profile of the subject to the temporal profile at a 450x450-pixel resolution.


Just to clarifying the below gif is imaging at 1 trillion frames per second. You can actually see light is slowed down enough to perceive it’s movement using one of these cameras.

8bitfuture:

Worlds fastest camera shoots 4.4 trillion frames per second.

A Japanese team has created a recording device able to acquire 4.4 trillion images per second, at a 450 x 450 pixel resolution. The technique could be used to further research into heat conduction and chemical reactions, according to its creators.

If the resolution can be improved, it could also prove useful for manufacturing, where it could keep track of laser cuttings in real time.

The technique, known as a Sequentially Timed All-optical Mapping Photography, or STAMP for short, shuns the conventional methods employed by other superspeed cameras to achieve results up to 1,000 times faster than has been previously available. The current leading brand of high-speed real-time recording is a method unfortunately known as the pump-probe process, where light is “pumped” at the subject and then “probed” for absorption. STAMP differs from this by skipping the need to constantly probe, or measure, the scene to construct an image, instead it uses single-shot bursts to acquire images and maps the spatial profile of the subject to the temporal profile at a 450x450-pixel resolution.

Just to clarifying the below gif is imaging at 1 trillion frames per second. You can actually see light is slowed down enough to perceive it’s movement using one of these cameras.