- SI unit of electric current, one of the seven SI base units
- one ampere = one coulomb of charge per second
- named after Andre-Marie Ampere, founder of electrodynamics
- redefined in 2019 by fixing the elementary charge at 1.602176634e-19 coulombs
- household circuits: 15-20 A (breaker rating)
- smartphone charging: ~1-3 A
- lightning bolt: ~20,000-200,000 A
- Ohm’s law: I = V / R (current = volt / resistance)
- electrical power: P = I * V (watt)
- milliamperes through the human heart can be lethal (~100 mA)