Semiconductors: Diode Forward Voltage Drop MCQ

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Diode Forward Voltage DropMediumQuestion 20228

Question

The forward voltage drop across a silicon diode at which it starts conducting significantly is approximately:

A
0.1 V
B
0.3 V
C
0.7 V
Correct
D
1.5 V

Correct answer

0.7 V

Explanation

Silicon diode knee voltage ≈ 0.7 V (Ge ≈ 0.3 V). Below this, very little current flows (exponential with low V_T). Above 0.7 V, current increases exponentially → the diode is 'ON'. In circuit analysis, silicon diode is often modelled as a 0.7 V battery in series with ideal diode.

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