Definition
An electrical current that flows in only one direction through a circuit, from the negative terminal of the source to the positive terminal. The voltage and current remain at a steady level rather than reversing direction over time.
Plain English
Electricity that flows one way only, like water moving steadily through a pipe in a single direction. Batteries produce this kind of electricity.
Context Anchor
Seen in aircraft electrical system descriptions, battery checks, charging system discussions, and equipment power requirements.
Derivation
From Latin directus, meaning 'straight' or 'in one line.' The current goes straight one way, never reversing — which is exactly what distinguishes it from alternating current.
Why Pilots Care
Aircraft batteries and many avionics systems operate on direct current; misidentifying power type during troubleshooting can lead to incorrect fault isolation or equipment damage.
Analogy
Direct current is like water flowing through a hose in one direction. The flow may get stronger or weaker, but it does not keep reversing direction.
Grounding Statement
In the cockpit, direct current travels from the battery through wires to instruments and lights without changing direction.
Intuition Check
“Direct” does not mean the electricity takes the shortest physical path. Here, it means the electrical flow keeps the same direction and polarity in the circuit.
Example Sentence 1
The aircraft's battery supplies direct current to the starter motor and the basic electrical bus.
Example Sentence 2
After the alternator rectifies its output, the system delivers direct current to charge the battery.