JEE Physics · Medium

Semiconductors: Mass Action Law MCQ

Solve this quality-checked JEE multiple-choice question, then review the correct answer and explanation.

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Mass Action LawMediumQuestion 20208

Question

The mass action law for a semiconductor states that:
  1. A
    n + p = constant
  2. B
    n × p = nᵢ² (constant at a given temperature)
    Correct
  3. C
    n/p = constant
  4. D
    n − p = nᵢ

Correct answer

n × p = nᵢ² (constant at a given temperature)

Explanation

Mass action law: np = nᵢ² regardless of doping. For intrinsic semiconductor: n = p = nᵢ. For n-type: n ≈ Nd >> nᵢ, so p = nᵢ²/Nd << nᵢ. Minority carriers decrease as majority increase.