The electrons don’t move very quickly either. And it’s current (amps = joules / second) times voltage (electric field potential difference) that delivers power.
Simplifying to a single harmonic (pure sine voltage source and a linear RLC load), you need to know the product of the voltage’s and current’s amplitude (in VA, voltamps) but also their power factor or cos φ, the cosine of phase beetween them. If the cosine is zero, it’s a purely reactive (L/C) load with a phase of ±90° and no power is consumed overall. If the cosine is negative, power is actually being generated by the device you’re measuring (for instance, old elevators and escalators with synchronous motors are actually delivering power into mains when enough people are travelling down).
The electrons don’t move very quickly either. And it’s current (amps = joules / second) times voltage (electric field potential difference) that delivers power.
Simplifying to a single harmonic (pure sine voltage source and a linear RLC load), you need to know the product of the voltage’s and current’s amplitude (in VA, voltamps) but also their power factor or cos φ, the cosine of phase beetween them. If the cosine is zero, it’s a purely reactive (L/C) load with a phase of ±90° and no power is consumed overall. If the cosine is negative, power is actually being generated by the device you’re measuring (for instance, old elevators and escalators with synchronous motors are actually delivering power into mains when enough people are travelling down).