File:Metal detector from World War 1.jpg
From Wikimedia Commons, the free media repository
Jump to navigation
Jump to search
Size of this preview: 800 × 419 pixels. Other resolutions: 320 × 168 pixels | 640 × 336 pixels | 1,024 × 537 pixels | 1,280 × 671 pixels | 2,144 × 1,124 pixels.
Original file (2,144 × 1,124 pixels, file size: 384 KB, MIME type: image/jpeg)
File information
Structured data
Captions
Summary[edit]
DescriptionMetal detector from World War 1.jpg |
English: An early experimental metal detector used for finding unexploded bombs in post World War 1 France. Named the "Alpha", it was designed by M. Guitton, professor of physics at Nancy. It used the principle of the "Hughes inductive balance" circuit invented by British scientist David Hughes in 1879. Each of the two separate coils mounted on the frame is a double coil or transformer, with the primary winding attached to a source of audio alternating current. The secondaries are wired in series with opposing phase to the operator's earphones. As long as there is no metal in range of the magnetic fields of the coils, the currents induced in the two secondary coils balance and cancel each other out, and no tone is heard. But if a piece of metal is in range, the eddy currents in it change the phase of the voltage induced in one of the secondaries, unbalancing the circuit, and a tone is heard. In use, the operator carried the frame around, sweeping the suspected area with the coils near the ground. An assistant followed, carrying the heavy control and battery box (box on ground). Both coils were sensitive, so when a signal was heard the operator had to determine by additional sweeps which coil the metal was near. The bulky instrument could fold up (left) for travelling. The device wasn't very sensitive compared to modern metal detectors; it could detect a 10 kg mass at a depth of 40 or 50 cm, and a smaller mass at a depth of 20 to 30 cm. |
Date | |
Source | Downloaded September 1, 2013 from F. Honoré, "Locating unexploded shells on the battlefields of France" in Scientific American (Scientific American Publishing Co., New York), Vol. 120, No. 16, p. 395 on Google Books |
Author | F. Honoré, |
Licensing[edit]
Public domainPublic domainfalsefalse |
This media file is in the public domain in the United States. This applies to U.S. works where the copyright has expired, often because its first publication occurred prior to January 1, 1929, and if not then due to lack of notice or renewal. See this page for further explanation.
|
||
This image might not be in the public domain outside of the United States; this especially applies in the countries and areas that do not apply the rule of the shorter term for US works, such as Canada, Mainland China (not Hong Kong or Macao), Germany, Mexico, and Switzerland. The creator and year of publication are essential information and must be provided. See Wikipedia:Public domain and Wikipedia:Copyrights for more details.
|
File history
Click on a date/time to view the file as it appeared at that time.
Date/Time | Thumbnail | Dimensions | User | Comment | |
---|---|---|---|---|---|
current | 11:21, 1 September 2013 | 2,144 × 1,124 (384 KB) | Chetvorno (talk | contribs) | User created page with UploadWizard |
You cannot overwrite this file.
File usage on Commons
There are no pages that use this file.
File usage on other wikis
The following other wikis use this file:
- Usage on en.wikipedia.org
- Usage on es.wikipedia.org
- Usage on eu.wikipedia.org
- Usage on fr.wikipedia.org
- Usage on vi.wikipedia.org
Metadata
This file contains additional information such as Exif metadata which may have been added by the digital camera, scanner, or software program used to create or digitize it. If the file has been modified from its original state, some details such as the timestamp may not fully reflect those of the original file. The timestamp is only as accurate as the clock in the camera, and it may be completely wrong.
JPEG file comment | Created with GIMP |
---|
Structured data
Items portrayed in this file
depicts
Hidden category: