Why is a photodiode operated in reverse bias whereas the current in forward bias is much larger than that in reverse bias? Explain. Mention its two uses.
Solution
A photodiode is operated in reverse bias because, on illumination, the light-generated carriers cause a large fractional change in the small reverse (minority-carrier) current, which is easily measured.
In forward bias the current is already large, so the same illumination produces only a negligible fractional change.
Two uses: (i) measurement/detection of light intensity (light sensors, exposure meters); (ii) optical and fibre-optic communication receivers.
In forward bias the current is already large, so the same illumination produces only a negligible fractional change.
Two uses: (i) measurement/detection of light intensity (light sensors, exposure meters); (ii) optical and fibre-optic communication receivers.
CBSE Class 12 Board · 2022 · Subjective