Why In a purely reactive component, voltage and current are 90 degrees out of phase, so energy flows into the component during one part of the cycle and back out to the source during the next. Over a full cycle the net energy dissipated is zero, so this apparent power does no work; it is measured in VAR (volt-amperes reactive) rather than watts. That is why it is called wattless or nonproductive power.
Watch out The choices about power consumed in inductors and capacitors or in an inductor's wire resistance describe real power: ideal reactances consume nothing, and any heating in the winding resistance is genuine I squared R dissipation, not reactive power.
Reactive power just sloshes back and forth: measured in VAR, not watts. No work done.