In a full-bridge rectifier, how many diodes conduct at any given half-cycle?

• A. One diode
• B. Two diodes conduct during one half-cycle
• C. Three diodes conduct
• D. All four diodes conduct simultaneously

Answer: (B)

Two diodes conduct during each half-cycle. In a full-bridge rectifier, the four diodes are arranged so that the current can always flow through the load in the same direction, no matter the input polarity. When the input is positive on one side, a pair of diagonally opposite diodes forward-bias and provide a complete path for current through the load; the other two diodes are reverse-biased and carry no current. When the input polarity reverses, the other pair becomes forward-biased and conducts, still delivering current in the same direction through the load. This is why the output is pulsating DC, with only two diodes conducting at any instant.