Elementary telegraphy : a manual for students; written specially to meet the requirements of the ordinary grade of the subject as published in the syllabus of the city and guilds of London Institute (1910)
Pendry, H. W. (Henry Walter) · London ; New York : Whittaker & Co. · leaf 65
, whatmethod of connecting the cells will give the greatest currentthrough an external resistance of 4 ? (h) Wliat will be thecurrent in niilli-amperes ? (Two rows of 4 : lOOO.) CHAPTER III xraKCRArii instruments The Morse key in its sinii)lest form as used in the PostOffice is shown in Fig. 26.… … Fig. 26. —Single current key. platinum is used being less oxidizable should sparkingoccur when tlie key is worked with large currents. Suchoxidation introduces resistance at the points of contact,sometimes causing even a disconnection. The back contactscrew carried by the lever is adjustable. The…
Telegraph
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