Experiments
Goldstein used a gas discharge tube which had a perforated cathode. When a high electrical potential of several thousand volts is applied between the cathode and anode, faint luminous "rays" are seen extending from the holes in the back of the cathode. These rays are beams of particles moving in a direction opposite to the "cathode rays," which are streams of electrons which move toward the anode. Goldstein called these positive rays Kanalstrahlen, "channel rays" or "canal rays", because they were produced by the holes or channels in the cathode. In 1907 a study of how this "ray" was deflected in a magnetic field, revealed that the particles making up the ray were not all the same mass. The lightest ones, formed when there was some hydrogen gas in the tube, were calculated to be about 1840 times as massive as an electron. They were protons.
The process by which anode rays are formed in a gas discharge tube is as follows. When the high voltage is applied to the tube, its electric field accelerates the small number of ions (electrically charged atoms) always present in the gas, created by natural processes such as radioactivity. These collide with atoms of the gas, knocking electrons off of them and creating more positive ions. These ions and electrons in turn strike more atoms, creating more positive ions in a chain reaction. The positive ions are all attracted to the negative cathode, and some pass through the holes in the cathode. These are the anode rays.
By the time they reach the cathode, the ions have been accelerated to a fast enough speed that when they collide with other atoms in the gas they excite the atom's orbital electrons to a higher energy level. When these electrons drop back to their former energy levels they release their energy as light. This light-producing process, called fluorescence, causes the beams of ions emerging from the cathode to glow. Canal rays are the rays that are produced by the ionization of the gas, the positive charged ions move towards the cathode and passed through the perforations of the cathode. As these perforations were named as canal so these rays are called canal rays. These are not the anode rays as these were not originated from the anode. However when cathode rays strike the anode these are highly accelerated and excite the atom's orbital electrons (of anode) to a higher energy level. When these electrons drop back to their former energy levels they release their energy as penetrating radiations of photons, discovered by Röntgen which he named x-rays. As these rays are originated from anode these are also called anode rays.
Read more about this topic: Anode Ray
Famous quotes containing the word experiments:
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—Denis Diderot (1713–1784)
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