| 单词 | electromagnetic radiation |
| 释义 | electromagnetic radiation Energy resulting from the acceleration of electric charge and the associated electric fields and magnetic fields. The energy can be regarded as waves propagated through space (requiring no supporting medium) involving oscillating electric and magnetic fields at right angles to each other and to the direction of propagation. In a vacuum the waves travel with a constant speed (the speed of light) of 2.9979 × 108 metres per second; if material is present they are slower. Alternatively, the energy can be regarded as a stream of photons travelling at the speed of light, each photon having an energy hc/λ, where h is the Planck constant, c is the speed of light, and λ is the wavelength of the associated wave. A fusion of these apparently conflicting concepts is possible using the methods of quantum mechanics or wave mechanics. The characteristics of the radiation depend on its wavelength. See electromagnetic spectrum |
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