Definition
The current that flows through a semiconductor diode or junction when it is forward biased — that is, when the positive terminal of the voltage source is connected to the anode and the negative terminal to the cathode. Under this condition the junction offers very low resistance and allows current to pass freely.
Plain English
The current that flows through a diode in the direction it is designed to allow. When the diode is connected the right way around, electricity passes through it easily.
Context Anchor
Seen in aircraft electrical-system study when discussing diodes, rectifiers, alternators, and solid-state circuits.
Derivation
‘Forward’ here means ‘in the intended direction of flow.’ A diode is built to pass current one way and block it the other. ‘Forward current’ is simply the current going the way the diode wants it to go.
Why Pilots Care
Aircraft power systems rely on forward current through diodes to convert alternating current to direct current and prevent damaging reverse flow that could drain the battery or damage components.
Analogy
A diode behaves like a one-way valve in a fuel line. Fluid moving in the intended direction passes through with little resistance — that flow is the equivalent of forward current. Flow attempted in the opposite direction is blocked.
Intuition Check
Forward does not mean physically toward the nose of the airplane here. It means the allowed direction of electrical flow through a one-way electronic part.
Example Sentence 1
When the diode is forward biased, forward current flows through the circuit and the indicator light comes on.
Example Sentence 2
A technician measures forward current through each diode to confirm the alternator is charging properly.