φ is the 2nd1th Greek letter. As a Greek lowercase letter, the bend in the upper left corner is φ of the opening; When used as a symbol, you usually write? .
The meaning of φ:
Lowercase φ:
Physics: representing magnetic flux or electric potential; Focal length; Glasses degree =-65438+φ to the 0 th power.
Engineering: indicates the diameter of a cylindrical material. For example, φ 10 means 10 unit diameters.
Φ in uppercase:
Physics: magnetic flux φ = bs; Fluctuation stage; Phase of current and voltage; The sign of the electric potential.
Mathematics: golden cutting rate; The number of yokes in a complex number; The included angle between the straight line and the z axis in three-dimensional coordinates; Euler function.
Engineering: indicates the diameter.