Whenever there is a great difference in phase in an alternating current
dynamo between volts and current, the true watts are much less than the
product of the virtual volts and amperes, because the the watts are
obtained by multiplying the product of the virtual volts and amperes by
the cosine of the angle of lag (or lead). Any alternating current may be
resolved into two components in quadrature with each other, one in phase
with the volts, the other in quadrature therewith, the former is termed
by S. P. Thompson the Working Current, the latter the Wattless Current.
The greater the angle of lag the greater will be the wattless current.