Which statement best describes a diode's current flow?

• A. Allows current to flow in both directions
• B. Allows current to flow in any one direction
• C. Blocks current in both directions
• D. Allows current to flow only when heated

Answer: (B)

Diodes enforce current in only one direction because of the PN junction inside. When the anode is driven more positive than the cathode (forward bias), charge carriers cross the junction and current flows, though it drops a small forward voltage (about 0.7 V for silicon). If the polarity is reversed (reverse bias), the depletion region widens and blocks current, so only a tiny leakage flows until breakdown. In practical terms, a diode provides a one-way path for current, unlike a conductor that carries current in both directions. Heating isn’t what enables conduction; it can affect performance but isn’t the controlling mechanism.