1º_ It is the letter efe of the Latin alphabet. In chemistry 'F' is the symbol for fluorine, in physics of the farad and the representation of a value of "force", in Anglo-Saxon musical notation it is the note F. In physics the 'f' represents the frequency, in mathematics it is a symbol for femto ( "factor of 10 8315; ¹ 8309;" ) . 'f . ' is short for folio and 'f/' for focal ratio in photography.
