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⚛️ Physics  ·  Semiconductor Electronics  ·  NEET & JEE

The forward characteristic of a diode shows a voltage change of 0.1 V producing a current change of 2 mA. Its dynamic resistance is:

Answer: 50.

  • A 50 Ω
  • B 20 Ω
  • C 0.02 Ω
  • D 200 Ω

Correct answer: A. 50 Ω

Explanation: Dynamic resistance r = &Delta;V/&Delta;I = 0.1 V / (2 &times; 10<sup>-3</sup> A) = 50 &Omega;.

Conductorconduction bandvalence bandbands overlapSemiconductorconduction bandvalence bandsmall gap (~1 eV)Insulatorconduction bandvalence bandlarge gap(> 3 eV)

Conductors have overlapping bands, semiconductors have a small energy gap that can be bridged by heat or doping, and insulators have a large gap that blocks conduction.

Concept context

Band theory, p-n junction, diodes, transistors, logic gates, and integrated circuits.

Read the full Semiconductor Electronics notes →