Ampere (A)

Quantity: Electric current · Category: SI base

The ampere is the SI base unit of electric current. Since 2019 it has been defined by the elementary charge: a current of one ampere is the flow of exactly 1/(1.602176634×10⁻¹⁹) elementary charges per second. It is named after André-Marie Ampère.

Relation to SI

Base unit — defined via e = 1.602176634×10⁻¹⁹ C exactly

Examples

• A phone charger delivers about 2 amperes.
• A lightning strike peaks near 30,000 amperes.