Ampere A
About the Ampere
The ampere is defined by fixing the elementary charge at exactly 1.602176634 × 10⁻¹⁹ coulombs, so one ampere is a flow of about 6.24 × 10¹⁸ elementary charges per second. Its previous definition, from 1948, was based on the force between two infinitely long parallel wires one metre apart. The unit is named after the French physicist André-Marie Ampère.
Related Units
Coulomb
C1 C = 1 A·s
The coulomb is the charge carried by a current of one ampere in one second. Since 2019 one coulomb is exactly...
Volt
V1 V = 1 W/A = 1 kg·m²·s⁻³·A⁻¹
A volt is the potential difference across a conductor when a current of one ampere dissipates one watt. It is named...
Ohm
Ω1 Ω = 1 V/A = 1 kg·m²·s⁻³·A⁻²
The ohm is the resistance that passes a current of one ampere under a potential difference of one volt. It is named...
Siemens
S1 S = 1 Ω⁻¹ = 1 kg⁻¹·m⁻²·s³·A²
The siemens measures conductance, the reciprocal of resistance, and replaced the informal mho (ohm spelled backwards)...