Sunday, December 19, 2021

History and discovery of X-ray

X-rays were discovered in 1895 by Wilhelm Conrad Röntgen who was a professor at the University of Wurzburg, Bavaria.

On 8 November 1895, Röntgen wrapped some black cardboard around a Crookes tube attached to a Ruhmkorff induction coil, in other words a step-up transformer excited by repeated electrical pulses. Every pulse produced an electric discharge in the low-pressure gas in the tube.
After turning off the lights in the room, he noticed that some crystals of barium platinocyanide, near a discharge tube completely enclosed in black pepper, became luminescent when the discharge occurred.

By examining the shadows cast by the rays, Rontgen traced the origin of the rays to the walls of the discharge tube.

Röntgen delivered the news on the 28th of December 1895. Emil Warburg relayed it to the Berlin Physical Society on the 4th of January.

He suggested the name “X-ray” for his discovery, arguing that since the origin of the rays was unknown, it was appropriate to refer to them as X, the mathematical term for the unknown.

For his work x-rays, Röntgen received the first Nobel prize in physics, in 1901. It was the first of six to be awarded in the field of x-rays by 1927.

On January 13, 1896, Röntgen traveled to Berlin, Germany, to demonstrate the production of X-rays to Emperor Wilhelm II. On January 23, 1896, Roentgen presented his paper and demonstrated the production of X-rays to the Physical Institute of Wurzburg in his only public lecture on this topic.

The obvious similarities with the light led to the crucial tests of established wave optics: polarization, diffraction, reflection and refraction.

With limited experimental facilities, Röntgen and his contemporaries could find no evidence of any of these; hence, the designation “x” (unknown) of the rays, generated by the stoppage of anode targets of the cathode rays, identified by Thompson in 1897 as electrons.

The essential wave nature of x-rays was established in 1912 by Laue, Friedrich, and Knipping, who showed that x-rays could be diffracted by a crystal (copper sulfate pentahydrate) that acted as a three-dimensional diffraction grating.

William Lawrence Bragg proposed a simple but powerful equation – which became known as Bragg’s law – showing the connection between the wavelength of the X-rays, the distance between the planes and the angle at which the X-rays are reflected.

In 1908, Barkla and Sadler deduced, by scattering experiments, that x-rays contained components characteristics of the material of the target; they called these component K and L radiations.
History and discovery of X-ray

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