Concept:A photodiode is a light-sensitive p-n junction diode operated in reverse bias to detect optical signals.
Explanation:When light strikes the junction, it generates electron-hole pairs.
Reverse bias creates a strong electric field that quickly sweeps these charge carriers, producing a photocurrent.
Thus, a photodiode is always operated in reverse bias.
The photocurrent mainly depends on the intensity of incident radiation, not on the reverse bias.
Option A is incorrect because photocurrent is not controlled by reverse bias.
Option B is incorrect because photocurrent definitely changes with incident radiation.
Option C is incorrect because forward bias is never used in a photodiode.
Answer:Option D: which is always operated in reverse bias.