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Semiconductors

JEE Main level, single correct, medium

121 of 209

Question 121 of 209

Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: Photodiodes are used in forward bias usually for measuring the light intensity.
Reason R: For a $p-n$ junction diode, at applied voltage $V$ the current in the forward bias is more than the current in the reverse bias for $\left|{V}_{z}\right|\gt \pm V\geq \left|{V}_{0}\right|$ where ${V}_{0}$ is the threshold voltage and ${V}_{z}$ is the breakdown voltage.
In the light of the above statements, choose the correct answer from the options given below

Show answer and solution

Answer: (C) A is false but R is true

Photodiodes are operated in reverse bias condition. The change in saturation reverse current in a photodiode with reverse bias is directly proportional to the change in light intensity, thus can be precisely measured.
Current in forward bias (for applied voltage

V\geq {V}_{0}

) is always greater than current in reverse bias (for

V\leq {V}_{z}

) in a

p-n

junction diode.
Hence, Assertion if false but Reason is true.

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JEE Main 2025 Apr 2 Shift 1 question paper

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