File:Refraction_of_Hertzian_waves_by_a_paraffin_lens_1897.png
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Refraction_of_Hertzian_waves_by_a_paraffin_lens_1897.png (593 × 275 pixels, file size: 17 KB, MIME type: image/png)
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Summary
DescriptionRefraction of Hertzian waves by a paraffin lens 1897.png |
English: Early experiment demonstrating refraction of microwaves by a paraffin lens, by John Ambrose Fleming in 1897, repeating similar earlier historic experiments around 1894 by Jagadish Chandra Bose, Oliver Lodge, and Augusto Righi. A spark gap transmitter A, consisting of a dipole antenna made of two brass rods with a spark gap between them inside an open waveguide, powered by an induction coil I generates a beam of microwave radio waves at a frequency of 1.5 GHz (20 centimeters wavelength). This is focused by the solid paraffin lens L on a dipole receiving antenna in the box B and detected by a coherer receiver, which rang a bell every time the transmitter was pulsed. Fleming demonstrated that the lens actually focused the waves by showing that when it was removed from the apparatus, the unfocused waves from the transmitter were too weak to activate the receiver. The historic importance of quazioptical exeriments like this is that they confirmed that radio waves and light waves are both electromagnetic waves, differing only in frequency. |
Date | |
Source | Retrieved 16 June 2020 from John Ambrose Fleming (1916) The Principles of Electric Wave Telegraphy and Telephony, 3rd Ed., Longmans, Green, & Co., London, p. 414, fig. 10 on Google Books |
Author | John Ambrose Fleming |
Licensing
Public domainPublic domainfalsefalse |
This work is in the public domain in its country of origin and other countries and areas where the copyright term is the author's life plus 70 years or fewer. This work is in the public domain in the United States because it was published (or registered with the U.S. Copyright Office) before January 1, 1929. | |
This file has been identified as being free of known restrictions under copyright law, including all related and neighboring rights. |
https://creativecommons.org/publicdomain/mark/1.0/PDMCreative Commons Public Domain Mark 1.0falsefalse
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Date/Time | Thumbnail | Dimensions | User | Comment | |
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current | 22:31, 16 June 2020 | 593 × 275 (17 KB) | Chetvorno | Uploaded a work by John Ambrose Fleming from Retrieved 16 June 2020 from [https://books.google.com/books?id=2RRLAAAAMAAJ&pg=PA414 John Ambrose Fleming (1916) ''The Principles of Electric Wave Telegraphy and Telephony, 3rd Ed.'', Longmans, Green, & Co., London, p. 414, fig. 10] on Google Books with UploadWizard |
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Horizontal resolution | 37.79 dpc |
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Vertical resolution | 37.79 dpc |
File change date and time | 22:07, 16 June 2020 |