1, the current is measured by the amount of electricity (current intensity) passing through the cross section of the conductor in unit time, and the capital letter I is usually used to represent the current in the formula. Q represents the amount of electricity passing through the conductor cross section per unit time (represented by the letter T). The current calculation formula is as follows: I = q/t.

2. In electromagnetism, the amount of electricity passing through any section of a conductor per unit time is called current intensity, which is called current for short. The symbol of current is I, and the unit is ampere (A), which is called "An" for short (André-Marie Ampère, 1775~ 1836, a French physicist and chemist, has made outstanding achievements in the research of electromagnetic action, and made contributions to both mathematics and physics. The international unit of current, ampere, is named after its surname.