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Question
Draw the circuit diagram of an illuminated photodiode in reverse bias. How is photodiode used to measure light intensity?
Solution
The circuit diagram of an illuminated photodiode in reverse bias can be represented as
The greater the intensity of light, the greater is the number of photons falling per second per unit area. Thus, the greater the intensity of light, the greater is the number of electron−hole pairs produced at the junction. The photocurrent is, thus, directly proportional to the intensity of light. This can be used for measuring the intensity of incident light.
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