A pn junction diode is forward biased when
- A. the p side is connected to the positive terminal and the n side to the negative
- B. the n side is connected to the positive terminal
- C. both sides are connected to the same terminal
- D. no voltage is applied
Explanation
Connecting positive to p repels holes and negative to n repels electrons, driving both towards the junction, so the depletion layer narrows and current flows once the applied voltage exceeds the barrier. Reverse bias does the opposite, widening the layer so that only a tiny leakage current passes. This one way behaviour is what makes the diode useful.