Resonator Resonator A resonator is a device or system that exhibits resonance or resonant behavior, that is, it naturally oscillates at some frequencies, called its resonant frequencies, with greater amplitude than at others. The oscillations in a resonator can be either electromagnetic or mechanical (including acoustic). Resonators are used to either generate waves of specific frequencies or to select specific frequencies from a signal. Musical instruments use acoustic resonators that produce sound waves of specific tones. Another example is quartz crystals used in electronic devices such as radio transmitters and quartz watches to produce oscillations of very precise frequency. A cavity
Conceptual metaphor Aristotle is often situated as the first commentator on the nature of metaphor, writing in the "Poetics", "A 'metaphorical term' involves the transferred use of a term that properly belongs to something else," and elsewhere in the "Rhetoric" he says that metaphors make learning pleasant; "To learn easily is naturally pleasant to all people, and words signify something, so whatever words create knowledge in us are the pleasantest." Aristotle's writings on metaphor constitute a "substitution view" of metaphor, wherein a metaphor is simply a decorative word or phrase substituted for a more ordinary one. This has been sometimes called the