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2 天前 · Electronic symbol. In electrical engineering, a capacitor is a device that stores electrical energy by accumulating electric charges on two closely spaced surfaces that are insulated from each other. The capacitor was originally known as the condenser, [1] a term still encountered in a few compound names, such as the condenser microphone.
2 天前 · The electron ( e− or β− ) is a subatomic particle with a negative one elementary electric charge.[13] Electrons belong to the first generation of the lepton particle family,[14] and are generally thought to be elementary particles because they have no known components or substructure.[1] The electron's mass is approximately 1/1836 that of ...
- stable ( > 6.6×10²⁸ yr)
- J. J. Thomson (1897)
- e−, β−
- −1 e, −1.602176634×10−19 C
1 天前 · The number π (/paɪ/; spelled out as "pi") is a mathematical constant that is the ratio of a circle's circumference to its diameter, approximately equal to 3.14159. The number π appears in many formulae across mathematics and physics. It is an irrational number, meaning that it cannot be expressed exactly as a ratio of two integers, although ...
2 天前 · Copper is a chemical element; it has symbol Cu (from Latin cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orange color. Copper is used as a conductor of heat and electricity, as a building material, and as a ...
3 天前 · Silicon is a chemical element; it has symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic table: carbon is above it; and germanium, tin, lead, and flerovium are below it. It is relatively unreactive ...
1 天前 · Eugenics (/juːˈdʒɛnɪks/ yoo-JEN-iks; from Ancient Greek εύ̃ (eû) 'good, well', and -γενής (genḗs) 'come into being, growing')[1] is a set of beliefs and practices that aim to improve the genetic quality of a human population.[2][3][4] Historically, eugenicists have attempted to alter human gene pools by excluding people and ...
13 小時前 · Mozilla Firefox, or simply Firefox, is a free and open-source[11] web browser developed by the Mozilla Foundation and its subsidiary, the Mozilla Corporation. It uses the Gecko rendering engine to display web pages, which implements current and anticipated web standards.[12] Firefox is available for Windows 10 or later versions, macOS, and ...
