No higher resolution available.
Wireless_power_demonstration_1937.jpg (745 × 339 pixels, file size: 55 KB, MIME type: image/jpeg)
 | This is a file from the Wikimedia Commons. Information from its description page there is shown below. Commons is a freely licensed media file repository. You can help. |
Summary
| Description |
English: A demonstration of wireless power transmission at the Franklin Institute, Philadelphia, USA in 1937. The device on the right is a radio transmitter that transmits power via shortwave radio waves to the receiver device at left, which lights the incandescent light shown. The transmitter consists of a triode vacuum tube oscillator, with the tank coil serving as an antenna. The simple receiver (left) is a tuned circuit consisting of an inductor coil and capacitor, tuned to the resonant frequency of the ocillator, with the light bulb in series. The inductor likewise serves as the receiving antenna. Visitors can adjust the inductor and capacitor with the two knobs visible on the left, and discover that if the receiver is brought out of resonance with the transmitter the light bulb will go out. The frequency may have been 60 MHz; the article is unclear. Nikola Tesla discovered this resonant inductive coupling power transfer technique around 1900. It is currently being applied to many short range wireless power systems. As the source points out, the radio waves spread out in all directions, so this technique cannot be used to transmit power long distances. |
| Date | |
| Source | Retrieved March 18, 2015 from "Lighting Lamp by S-W Radio" in Short Wave and Television magazine, Popular Book Corp., New York, Vol. 8, No. 4, August 1937, p. 166 on http://www.americanradiohistory.com |
| Author | Unknown author |
| Permission (Reusing this file) |
This 1937 issue of Short Wave and Television magazine would have the copyright renewed in 1965. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here. Search of the Renewals for Periodicals for 1964, 1965, and 1966 show no renewal entries for Short Wave and Television. Therefore the copyright was not renewed and it is in the public domain. |
Licensing
|
This work is in the public domain because it was published in the United States between 1929 and 1963, and although there may or may not have been a copyright notice, the copyright was not renewed. For further explanation, see Commons:Hirtle chart and the copyright renewal logs. Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.
|
 |
File history
Click on a date/time to view the file as it appeared at that time.
| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 10:56, 22 March 2015 | | 745 × 339 (55 KB) | Chetvorno | User created page with UploadWizard |
File usage
The following pages on the English Wikipedia use this file (pages on other projects are not listed):
