Free Online ampere Converter
ampere
Definition: The ampere (symbol: A), often referred to as simply amp, is the base unit of electric current in the International System of Units (SI). The ampere is defined formally based on a fixed value for the elementary charge, e, of 1.602176634 × 10-19 when expressed in the unit C, which is equal to A·s. The second is defined based on the cesium frequency, ΔνCs. This definition is effective since 2019, and is a significant change from the previous definition of the ampere.
History/origin: The ampere is named after Andre-Marie Ampere, a French mathematician and physicist. In the centimeter-gram-second system of units, the ampere was defined as one tenth of the unit of electrical current of the time, which is now known as the abampere. The size of the unit was chosen such that it would fit conveniently within the metre-kilogram-second system of units. Before 2019, the ampere was defined formally as the constant current at which a force of 2 × 10-7 newtons per meter length would be produced between two conductors, where the conductors are parallel, have infinite length, are placed in a vacuum, and have negligible circular cross-sections. In terms of the SI unit of charge, the coulomb, one ampere is defined as one coulomb of charge passing through a given point in one second. This definition was difficult to realize with high precision, and as such was changed to be more intuitive, and easier to realize. Previously, since the definition included a reference to force, the SI kg, meter, and second needed to be defined before the ampere could be defined. Now, it is only dependent on the definition of the second. One potential drawback of the redefinition is that vacuum permeability, vacuum permittivity, and impedance of free space were exact before the redefinition, but will now be subject to experimental error.
Current use: As the SI base unit of electric current, the ampere is used worldwide for almost all applications involving electric current. An ampere can be expressed in the form of watts/volts, or W/V, such that an ampere equals 1 W/V, since power is defined as a product of current and voltage.
