Suppose that I have two sources: 1. 24 VAC, 60 Hz and 2. 24 VAC, 20 Hz Then I will use it to power into certain load (maybe we can assume a purely resistive load to simplify the question). What would be the effect of those sources to the load? How about the current flowing? I think (1) and (2) would produce same magnitude but does its frequency follows the the frequency of inputs? or it will differ?