- Anonymous1 decade agoFavorite Answer
RADAR is a system used to detect, range (determine the distance of), and map objects such as aircraft, ships, and rain, that was first suggested as a "ship finder" by Dr. Allen B. DuMont in 1932. Coined in 1941 as an acronym for Radio Detection and Ranging, it has since entered the English language as a standard word, losing the capitalization in the process.
Electromagnetism is the physics of the electromagnetic field: a field, encompassing all of space, which exerts a force on those particles that possess the property of electric charge, and is in turn affected by the presence and motion of such particles. The term electrodynamics is sometimes used to refer to the combination of electromagnetism with mechanics, and deals with the effects of the electromagnetic field on the dynamic behavior of electrically charged particles. Electromagnetism encompasses various real-world electromagnetic phenomena.
分子增幅器(MASER), Microwave Amplification by Stimulated Emission of Radiation
A maser is a device that produces coherent electromagnetic waves through amplification due to stimulated emission. Historically the term came from the acronym "microwave amplification by stimulated emission of radiation", although modern masers emit over a broad portion of the electromagnetic spectrum. This has led some to replace "microwave" with "molecular" in the acronym, as suggested by Townes . When optical coherent oscillators were first developed, they were called optical masers, but it has become more common to refer to these as lasers. See the section on terminology below for more on this.
2006-03-30 22:04:28 補充：
雷達原文應為Radar, 上面第一排打錯了, sorry!! @_@Source(s): http://en.wikipedia.org/wiki/Main_Page
- gundamppLv 51 decade ago
RADAR=(Ra)dio (D)etection (a)nd (R)anging