{"topic":"dflmge","count":1,"articles":[{"id":"britannica-11-dflmge","work_id":"britannica-11","title":"Dflmge","normalized_title":"dflmge","slug":"dflmge","aliases":[],"subtitle":"Internet Archive OCR import","body_text":"DFLMGE, HLMJ are in resonance that a considerable current will Bow round the latter. Hence when we get a maximum effect in the detector we know that the waves we are dealing with are those corresponding to the free periods of the system HLMJ, so that if we know the free periods of this circuit we know the wave length of the electric waves under consideration. Thus if the ends of the wires H, J are free and have no capacity, the current along them must vanish at H and J, which must be in opposite electric condition. Hence half the wave length must be an odd submultiple of the length of the circuit HLMJ. If H and J are connected together the wave length must be a submultiple of the length of this circuit. When the capacity at the ends is appreciable the wave length of the circuit is FIG. 8. determined by a somewhat complex expression. To facilitate the determination of the wave length in such cases, Lecher introduced a second bridge L'M', and moved this about until the deflection of the detector was a maximum; when this occurs the wave length is one of those corresponding to the closed circuit LMM'L', and must therefore be a submultiple of the length of the circuit. Lecher showed that if instead of using a single wire LM to form the bridge, he used two parallel wires PQ, LM, placed close together, the currents in the further circuit were hardly appreciably diminished when the main wires were cut between PL and QM. Blondlot used a modification of this apparatus better suited for the production of short waves. In his form (fig. 9) the exciter consists of two semicircular arms connected with the terminals of an induction coil, and the long wires, instead of being connected with the small plates, form a circuit round the exciter. As an example of the use of Lecher's arrangement, we may quote Urude s application of the method to find the specific induction capacity of dielectrics under electric oscillations of varying frequency. In this application the ends of the wire are connected to the plates of a condenser, the space between whose plates can be filled with the liquid whose specific inductive capacity is required, and the bndge is moved until the detector at the end of the circuit gives the maximum deflection. Then if X is the wave length of the waves, X is the wave length of one of the free vibrations of the system HLMJ; hence if C is the. capacity of the condenser < at the end in electrostatic measure we have where / is the distance of the condenser from the bridge and C' is the capacity of unit length of the wire. In the condenser part of the lines of force will pass through air and part through the dielectric; hence C will be of the form Co+KCi where K is the specific inductive capacity of the dielectric. Hence if / is the distance of maximum deflection when the dielectric is replaced by air, /' when filled with a dielectric whose specific inductive capacity is known to be K', and /' the distance when filled with the dielectric whose specific inductive capacity is required, we easily see that — cot^-cotlT i-K' 271 2lrP = I-K cot—. cot— r—","body_html":"

DFLMGE, HLMJ are in resonance that a considerable current will Bow round the latter. Hence when we get a maximum effect in the detector we know that the waves we are dealing with are those corresponding to the free periods of the system HLMJ, so that if we know the free periods of this circuit we know the wave length of the electric waves under consideration. Thus if the ends of the wires H, J are free and have no capacity, the current along them must vanish at H and J, which must be in opposite electric condition. Hence half the wave length must be an odd submultiple of the length of the circuit HLMJ. If H and J are connected together the wave length must be a submultiple of the length of this circuit. When the capacity at the ends is appreciable the wave length of the circuit is FIG. 8. determined by a somewhat complex expression. To facilitate the determination of the wave length in such cases, Lecher introduced a second bridge L'M', and moved this about until the deflection of the detector was a maximum; when this occurs the wave length is one of those corresponding to the closed circuit LMM'L', and must therefore be a submultiple of the length of the circuit.

\n

Lecher showed that if instead of using a single wire LM to form the bridge, he used two parallel wires PQ, LM, placed close together, the currents in the further circuit were hardly appreciably diminished when the main wires were cut between PL and QM. Blondlot used a modification of this apparatus better suited for the production of short waves. In his form (fig. 9) the exciter consists of two semicircular arms connected with the terminals of an induction coil, and the long wires, instead of being connected with the small plates, form a circuit round the exciter. As an example of the use of Lecher's arrangement, we may quote Urude s application of the method to find the specific induction capacity of dielectrics under electric oscillations of varying frequency. In this application the ends of the wire are connected to the plates of a condenser, the space between whose plates can be filled with the liquid whose specific inductive capacity is required, and the bndge is moved until the detector at the end of the circuit gives the maximum deflection.

\n

Then if X is the wave length of the waves, X is the wave length of one of the free vibrations of the system HLMJ; hence if C is the. capacity of the condenser < at the end in electrostatic measure we have where / is the distance of the condenser from the bridge and C' is the capacity of unit length of the wire. In the condenser part of the lines of force will pass through air and part through the dielectric; hence C will be of the form Co+KCi where K is the specific inductive capacity of the dielectric. Hence if / is the distance of maximum deflection when the dielectric is replaced by air, /' when filled with a dielectric whose specific inductive capacity is known to be K', and /' the distance when filled with the dielectric whose specific inductive capacity is required, we easily see that — cot^-cotlT i-K' 271 2lrP = I-K cot—. cot— r—

","volume_id":"britannica-11-v9","page_range_label":"Vol. 9, pp. 207-207","source_url":"https://archive.org/details/encyclopaediabrit09chisrich/page/n230/mode/1up","text_source_url":"https://archive.org/download/encyclopaediabrit09chisrich/encyclopaediabrit09chisrich_djvu.txt","scan_source_url":"https://archive.org/details/encyclopaediabrit09chisrich","quality_status":"ocr-imported-page-aligned","parser_version":"ia-djvu-xml-v1","page_refs":[{"page_number":"207","label":"p. 207","image_url":"/source-assets/scans/britannica-11/encyclopaediabrit09chisrich/encyclopaediabrit09chisrich_0231.jpg","source_image_url":"https://archive.org/download/encyclopaediabrit09chisrich/encyclopaediabrit09chisrich_jp2.zip/encyclopaediabrit09chisrich_jp2%2Fencyclopaediabrit09chisrich_0231.jp2&ext=jpg","source_url":"https://archive.org/details/encyclopaediabrit09chisrich/page/n230/mode/1up"}],"work":{"id":"britannica-11","slug":"britannica-11","title":"Encyclopaedia Britannica","short_title":"Britannica 11th","edition":"11th edition","publisher":"Cambridge University Press","publication_start_year":1910,"publication_end_year":1911,"language":"English","country":"United Kingdom / United States","copyright_status_note":"First published before 1931; treated as public domain in the United States. Verify jurisdiction before redistribution outside the U.S.","source_quality":"mixed-clean-and-ocr","text_source_url":"https://en.wikisource.org/wiki/1911_Encyclop%C3%A6dia_Britannica","scan_source_url":"https://archive.org/details/encyclopaediabri","volumes":[{"id":"britannica-11-v1","volume_number":"1","title":"A to Androphagi","year":1910,"source_url":"https://archive.org/details/encyclopaediabri01chisrich","text_source_url":"https://en.wikisource.org/wiki/1911_Encyclop%C3%A6dia_Britannica","scan_source_url":"https://archive.org/details/encyclopaediabri01chisrich","page_count":1084},{"id":"britannica-11-v2","volume_number":"2","title":"Andros to Austria","year":1910,"source_url":"https://archive.org/details/encyclopaediabri02chisrich","text_source_url":"https://archive.org/download/encyclopaediabri02chisrich/encyclopaediabri02chisrich_djvu.txt","scan_source_url":"https://archive.org/details/encyclopaediabri02chisrich","page_count":null},{"id":"britannica-11-v9","volume_number":"9","title":"Edwardes to Evangelical Association","year":1910,"source_url":"https://archive.org/details/encyclopaediabrit09chisrich","text_source_url":"https://archive.org/download/encyclopaediabrit09chisrich/encyclopaediabrit09chisrich_djvu.txt","scan_source_url":"https://archive.org/details/encyclopaediabrit09chisrich","page_count":null},{"id":"britannica-11-v26","volume_number":"26","title":"Submarine Mines to Tom-Tom","year":1911,"source_url":"https://archive.org/details/encyclopaediabri26chisrich","text_source_url":"https://archive.org/download/encyclopaediabri26chisrich/encyclopaediabri26chisrich_djvu.txt","scan_source_url":"https://archive.org/details/encyclopaediabri26chisrich","page_count":null},{"id":"britannica-11-v27","volume_number":"27","title":"Tonality to Vesuvius","year":1911,"source_url":"https://archive.org/details/encyclopaediabri27chisrich","text_source_url":"https://ia903207.us.archive.org/15/items/encyclopaediabri27chisrich/encyclopaediabri27chisrich_djvu.txt","scan_source_url":"https://archive.org/details/encyclopaediabri27chisrich","page_count":null}]}}]}