| 单词 | electron |
| 释义 | electron An elementary particle of matter that carries a negative charge of approximately 1.6021 × 10-19 coulomb (C) and having a mass, when at rest, of approximately 9.109534 × 10-28 grams, which is 1⁄1836 the mass of a proton. Ordinarily, an atom has the same number of negatively charged electrons orbiting the nucleus as there are positively charged protons within the nucleus. Electrons are the moving matter that contributes the most to electric currents and voltages. Metals are conductors of electricity as they contain free electrons, also known as conduction electrons. Copper is a particularly good conductor as each copper atom contains one free electron, i.e., one electron that is free to detach from an atom and to flow through the conductor when voltage is applied to create current. Coined by George Johnstone Stoney in 1891, the word is from the Greek elektron, meaning amber. ( Note: When rubbed against wool, amber, which is fossilized tree sap, attracts free electrons from the wool and becomes negatively charged and will attract small objects that are positively charged through a process known as electrostatic induction. If rubbed long enough and electrostatically charged enough, amber will generate sparks of static electricity.) See also coulomb, current, inductance, and voltage. |
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