Definition
A direct current whose magnitude rises and falls repeatedly but never reverses direction. The current always flows the same way through the circuit, but its strength varies in a regular pattern rather than holding a steady value.
Plain English
Electricity that flows in only one direction, but in pulses — strong, weaker, strong, weaker — instead of at a constant level.
Context Anchor
Seen in aircraft electrical-system troubleshooting, especially when checking whether a DC power output is steady or has a repeating rise-and-fall pattern.
Derivation
From Latin pulsare, 'to beat or throb.' The word captures the idea of a current that beats up and down like a pulse, while still flowing one way only.
Why Pilots Care
Unfiltered pulsating DC can create electrical noise that interferes with avionics and instruments if not smoothed by capacitors or regulators.
Analogy
It is like water moving through a hose in only one direction, but surging with each pump stroke instead of flowing smoothly.
Intuition Check
Do not confuse pulsating DC with AC. Pulsating DC changes in strength, but it still flows in one direction; AC reverses direction.
Example Sentence 1
After the rectifier converts the alternator's output, the result is pulsating DC, which is then smoothed by a filter before reaching the avionics.
Example Sentence 2
Mechanics check for excessive ripple in pulsating DC when troubleshooting charging system issues.