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Cathode rays are invisible, but their presence was first detected in these Crookes tubes when they struck the glass wall of the tube, exciting the atoms of the glass coating and causing them to emit light, a glow called fluorescence. Researchers noticed that objects placed in the tube in front of the cathode could cast a shadow on the glowing ...
The cathode-ray tube by which J. J. Thomson demonstrated that cathode rays could be deflected by a magnetic field, and that their negative charge was not a separate phenomenon While supporters of the aetherial theory accepted the possibility that negatively charged particles are produced in Crookes tubes , [ citation needed ] they believed that ...
The term cathode ray was used to describe electron beams when they were first discovered, before it was understood that what was emitted from the cathode was a beam of electrons. In CRT TVs and computer monitors, the entire front area of the tube is scanned repeatedly and systematically in a fixed pattern called a raster .
Crookes X-ray tube from around 1910 Another Crookes x-ray tube. The device attached to the neck of the tube (right) is an "osmotic softener". When the voltage applied to a Crookes tube is high enough, around 5,000 volts or greater, [16] it can accelerate the electrons to a high enough velocity to create X-rays when they hit the anode or the glass wall of the tube.
In the 1870s, Goldstein undertook his own investigations of discharge tubes and named the light emissions studied by others Kathodenstrahlen, or cathode rays. [3] He discovered several important properties of cathode rays, which contributed to their later identification as the first subatomic particle, the electron. He found that cathode rays ...
He also investigated the light spectra of gases and vapours, worked on the passage of electricity through gases, and discovered new properties of cathode rays (electron rays). In 1869 he ascertained that the cathode rays glowed different colours because of different gasses and pressures.
When current was applied, it was found that the glass envelope of these tubes would glow at the end opposite to the cathode. Observing that sharp-edged shadows were cast on the glowing tube wall by obstructions in the tube in front of the cathode, Johann Hittorf realized that the glow was caused by some type of ray travelling in straight lines ...
He developed a version of the cathode tube and studied the penetration by X-rays of various materials. However, Lenard did not realize that he was producing X-rays. Hermann von Helmholtz formulated mathematical equations for X-rays. He postulated a dispersion theory before Röntgen made his discovery and announcement