Monday, November 8, 2010

115 Years of Knowing About X-Rays

The Electromagnetic Spectrum, Imagers, NASA Science for Kids

"As the wavelengths of light decrease, they increase in energy. X-rays have smaller wavelengths and therefore higher energy than ultraviolet waves. We usually talk about X-rays in terms of their energy rather than wavelength. This is partially because X-rays have very small wavelengths. It is also because X-ray light tends to act more like a particle than a wave. X-ray detectors collect actual photons of X-ray light - which is very different from the radio telescopes that have large dishes designed to focus radio waves!

""X-rays were first observed and documented in 1895 by Wilhelm Conrad Roentgen, a German scientist who found them quite by accident when experimenting with vacuum tubes...."

NASA Science for Kids is, as the name implies, written for "kids." My guess is that the target age is around ten or 11: but that's just a guess. It's a pretty good introduction to X-rays - and includes more photos. Including a set that shows what a supernova remnant looks like in radio, visible, and X-ray wavelengths.

Here's something a little more 'grown up,' on the same topic:

"115-Year-Old X-Ray"
National Geographic (November 8, 2010)

"This 115-year-old picture of fingers is one of the first images ever made with x-rays, whose discovery is being feted Monday with an anniversary Google doodle.

"The hand belonged to Anna Bertha, wife of German physicist Wilhelm Röntgen, the discover of x-rays. The black glob on the fourth finger is a ring made of gold, which absorbs x-rays.

"Röntgen stumbled across x-rays on November 8, 1895, while experimenting with an early vacuum tube known as a Crooke's radiometer. He noticed that, when the cathode rays from the tube struck the end of a discharge tube, a previously unknown type of radiation that could penetrate matter was emitted.

"Röntgen created the picture of his wife's hand using the unknown, or x, rays a few days later...."

I'd show you a copy of the Google doodle for the 115th anniversary of the discovery of X-rays, but Google has a politely-worded but definite policy about using the things:

"...Please don't use them elsewhere as each has a special history at Google and we'd like them to enjoy their well-deserved retirement."
("Official Logos," Google)

It's their logo, their intellectual property: and that's the way they want it used. I've written about this sort of thing before.

The National Geographic article is much shorter than the NASA page - and is more of a 'this day in history' item. Not all that much about X-rays as such.

The Mayo Clinic has a bit more to say on the subject: from a medical point of view, of course.



"An X-ray is a quick, painless test that produces images of the structures inside your body — particularly your bones.

"X-ray beams can pass through your body, but they are absorbed in different amounts depending on the density of the material they pass through. Dense materials, such as bone and metal, show up as white on X-rays. The air in your lungs shows up as black. Fat and muscle look like varying shades of gray...."

Okay: The Lemming doubts that the article will make a nationwide bestseller list any time soon: but it's quite informative.


Mr Lonely said...

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Brian, aka Aluwir, aka Norski said...

The blog in question is called "! A Growing Teenager Diary !"

It's done by someone who doesn't use capital letters, but does use punctuation.

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