Signalling through space without wires : being a description of the work of Hertz & his successors (1900)
Lodge, Oliver, Sir, 1851-1940, Hertz, Heinrich, 1857-1894 · London : "The Electrician" Printing and Publishing Company, Limited · leaf 134
en thepressure is *1 to -01 mm. of mercury. The resistance whichrarefied gas opposes to an electric current in a magnetic fieldis greatest in the direction normal to the magnetic lines.The changes of resistance effected by any kind of light in avacuum tube with alkali metal cathode can be… … Fig. 64.Explanation of Fig. 64. —A vacuum tube of rarefied hydrogen containingalkali metal as cathode, say the liquid K—Na alloy, or solid K or Na. Aspark gap at S serves as alternative path, and a stream of sparks can occurto the plate P in the dark. But when light falls on the surface A…
Electric waves · Telegraph, Wireless · Electricity · Wireless Technology
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