In mathematics, if |a|=2 (absolute value), the actual value of a is 2. Numbers greater than 0 are called positive numbers. Positive numbers are usually preceded by a "+"symbol, which can usually be omitted. There are countless kinds of positive numbers, including positive integers, positive fractions and positive irrational numbers. Numbers less than 0 are called negative numbers, and negative numbers and positive numbers represent quantities with opposite meanings. Negative numbers are marked with a negative sign "-"and a positive number.
Symbol in physics is not a single concept. The symbols used in physics are sometimes equivalent to the symbols of rational numbers in mathematics, and sometimes used to express the nature and direction of physical quantities. ?
Extended data
First, the meaning of symbols in electrostatics
1, coulomb force (electric field force) and electric field intensity are vectors, and their symbols indicate whether their directions are the same (+) or opposite to the specified positive direction.
2. The work done by electric field force is a scalar, and its positive and negative sign indicates whether the directions of electric field force and displacement are the same or opposite, and its absolute value indicates the magnitude of work done.
3. The amount of charge is a scalar, and its sign indicates the electrical property of the charge ("+"means positive charge and "-"means negative charge), and the size of the charge is the absolute value of the charge.
4. The potential is also a scalar, and its sign indicates the size. The negative potential is always lower than the positive potential.
It can be seen that the symbols in electrostatics do not represent size (height) in many cases, but have other specific meanings.
Second, the processing method of symbols in electrostatics
When dealing with the synthesis of coulomb force (electric field force) and electric field intensity, vector arithmetic is often used. After decomposition by orthogonal decomposition method, a positive direction is defined, vector operation is transformed into algebraic operation on the same line, and the direction of vector is represented by symbols. However, care should be taken not to replace the symbol indicating the electrical characteristics of the charge, which will lead to errors.
Baidu Encyclopedia-plus sign or minus sign