Cause Effect Essays. 1  Examine why something has happened or exists. 2  Speculate about what caused the situation. 3  Examine the results of an event, choice, or situation. 4  Trace the start of a situation to a discussion of its results.
Since 1990, the Food and Drug Administration (FDA) has required that medical device manufacturers that want to market certain categories of medical devices in the USA follow Design Control requirements (21 CFR 820.30). Clear documentation of the entire process in a design history file or DHF.
Fig 1: Input voltage and current waveforms for a device with PF = 1.0. In practice, some devices do have unity power factors, but many others do not. A device has a poor power factor for one of two reasons; either it draws current out of phase with the supply voltage, or it draws current in a non-sinusoidal waveform.