Corona discharge with a discharge current of a few hundred microamperes can blow out a small candle flame within about 1 cm of a discharge point. A pinwheel, with radial metal spokes and pointed tips bent to point along the circumference of a circle, can be made to rotate if energized by a corona discharge; the rotation is due to differential electric attraction between the metal spokes and the space charge shield region that surrounds the tips. Corona discharge A corona discharge is an electrical discharge brought on by the ionization of a fluid such as air surrounding a conductor that is
Meaning (philosophy of language) individual speaker in a particular context wants to refer to. The word "dog" is an example of a meaning, but pointing at a nearby dog and shouting "This dog smells foul!" is an example of usage. From this distinction between usage and meaning arose the divide between the fields of Pragmatics and Semantics. Yet another distinction is of some utility in discussing language: "mentioning". "Mention" is when an expression refers to itself as a linguistic item, usually surrounded by quotation marks. For instance, in the expression "'Opopanax' is hard to spell", what is referred to is the word itself ("opopanax")