folded spectrum technique
21Mirror — looking glass redirects here. For other uses, see Looking Glass (disambiguation). This article is about wave reflectors (mainly, specular reflection of visible light). For other uses, see Mirror (disambiguation). A mirror, reflecting a vase A… …
22Gramophone record — A 12 inch (30 cm) 33⅓ rpm record (left), a 7 inch 45 rpm record (right), and a CD (above) A gramophone record, commonly known as a phonograph record (in American English), vinyl record (in reference to vinyl, the material most commonly used after …
23Dirac delta function — Schematic representation of the Dirac delta function by a line surmounted by an arrow. The height of the arrow is usually used to specify the value of any multiplicative constant, which will give the area under the function. The other convention… …
24History of the floppy disk — 8 inch, 5¼ inch, and 3½ inch floppy disks Over the history of the floppy disk a number of different formats were used. Floppy disks have now been largely superseded by other storage media and by network file transfer. Contents …
25Germany — /jerr meuh nee/, n. a republic in central Europe: after World War II divided into four zones, British, French, U.S., and Soviet, and in 1949 into East Germany and West Germany; East and West Germany were reunited in 1990. 84,068,216; 137,852 sq.… …
26Headphones — For other uses, see Headphones (disambiguation). Sennheiser HD555 headphones, used in audio production environments …
27arctic — arctically, adv. /ahrk tik/ or, esp. for 7, /ahr tik/, adj. 1. (often cap.) of, pertaining to, or located at or near the North Pole: the arctic region. 2. coming from the North Pole or the arctic region: an arctic wind. 3. characteristic of the… …
28United Kingdom — a kingdom in NW Europe, consisting of Great Britain and Northern Ireland: formerly comprising Great Britain and Ireland 1801 1922. 58,610,182; 94,242 sq. mi. (244,100 sq. km). Cap.: London. Abbr.: U.K. Official name, United Kingdom of Great… …
29History of sound recording — Methods and media for sound recording are varied and have undergone significant changes between the first time sound was actually recorded for later playback until now. Technology Mechanical recording The first devices for recording sound were… …
30Capacitor — This article is about the electronic component. For the physical phenomenon, see capacitance. For an overview of various kinds of capacitors, see types of capacitor. Capacitor Modern capacitors, by a cm ruler Type Passive …
