height-frequency characteristic
71star — starless, adj. /stahr/, n., adj., v., starred, starring. n. 1. any of the heavenly bodies, except the moon, appearing as fixed luminous points in the sky at night. 2. Astron. any of the large, self luminous, heavenly bodies, as the sun, Polaris,… …
72Hard disk drive — Hard drive redirects here. For other uses, see Hard drive (disambiguation). Hard disk drive Mechanical interior of a modern hard disk drive Date invented 24 December 1954 [1] …
73human development — ▪ biology Introduction the process of growth and change that takes place between birth and maturity. Human growth is far from being a simple and uniform process of becoming taller or larger. As a child (child development) gets bigger,… …
74radiation measurement — ▪ technology Introduction technique for detecting the intensity and characteristics of ionizing radiation, such as alpha, beta, and gamma rays or neutrons, for the purpose of measurement. The term ionizing radiation refers to those… …
75Ionosphere — The ionosphere is a part of the upper atmosphere, comprising portions of the mesosphere, thermosphere and exosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner …
76TV and FM DX — TV DX and FM DX is the active search for distant radio or television stations received during unusual atmospheric conditions. The term DX is an old telegraphic term meaning long distance. VHF/UHF television and radio signals are normally limited… …
77Egypt — /ee jipt/, n. 1. Arab Republic of. a republic in NE Africa. 64,791,891; 386,198 sq. mi. (1,000,252 sq. km). Cap.: Cairo. Arabic, Misr. Formerly (1958 71), United Arab Republic. 2. an ancient kingdom in NE Africa: divided into the Nile Delta… …
78tornado — tornadic /tawr nad ik, nay dik/, adj. tornadolike, adj. /tawr nay doh/, n., pl. tornadoes, tornados. 1. a localized, violently destructive windstorm occurring over land, esp. in the Middle West, and characterized by a long, funnel shaped cloud… …
79Defining equation (physics) — For common nomenclature of base quantities used in this article, see Physical quantity. For 4 vector modifications used in relativity, see Four vector. Very often defining equations are in the form of a constitutive equation, since parameters of… …
80Speed of sound — Sound is a vibration that travels through an elastic medium as a wave. The speed of sound describes how much distance such a wave travels in a certain amount of time. In SI Units with dry air at 20 °C (68 °F), the speed of sound is 343 m/s. This… …
