Файл:Brockhaus-Efron Oscillation 3.jpg
| Описание |
Русский: Иллюстрация к статье Электрические колебания из энциклопедии Брокгауза и Ефрона
English: Illustration of a Lecher line, an experimental method of measuring the wavelength of radio waves developed by Ernst Lecher in 1888. The spark-gap transmitter (right), a primitive radio transmitter consisting of a half-wave dipole antenna| (A1, A2) with a spark gap between the elements excited by an induction coil, produced radio waves which were coupled into the parallel-wire transmission line (D1, D2) through the capacitors (A1, B1) and (A2, B2). They travelled down the line and were reflected back by the open circuit (E2) at the end. The returning reflected waves interfere with the outgoing waves to create standing waves along the line. At intervals of one-half wavelength the waves interfere destructively to create a node, a point where the voltage goes to zero. By sliding a thin Geissler tube (neon light) along the wires until its light went out, the location of the nodes could be determined, and by measuring the distance between them and multiplying by two the wavelength of the radio waves could be found. The frequency of the waves could be found by dividing the speed of light by the wavelength. Lecher lines were a common method of measuring frequency up until World War 2. |
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| Дата | около 1905 | ||||||
| Источник | Brockhaus and Efron Encyclopedic Dictionary, Moscow, ~1905 | ||||||
| Автор | Брокгауз и Ефрон | ||||||
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| текущий | 22:27, 23 июня 2009 | | 561 × 309 (28 КБ) | wikimediacommons>Lozman | {{Information |Description={{ru|Иллюстрация к статье ''Электрические колебания'' из энциклопедии Брокгауза и Ефрона}} |Source=http://dic.academic.ru/dic.nsf/brokgauz_efron/146322 |Date= |
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