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Semiconductor Electronic: Material, Devices And Simple Circuits — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsSemiconductor Electronic: Material, Devices And Simple Circuits1 Mark
Question
Two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from thecodes(a), (b), (c) and (d) as given below.
  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true but R is not the correct explanation of A.
  3. A is true but R is false.
  4. A is false and R is also false.
Assertion: The resistance of p-n junction is low when forward biased and is high when reverse biased.
Reason: In reversed biased, the depletion layer is reduced.
✓

Answer

  1. A is true but R is false.

Explanation:

A small increase in forward voltage across p-n junction shows large increase in forward current. Hence the resistance $\Big(=\frac{\text{Voltege}}{\text{Current}}\Big)$ 0f p-n junction is low when forward biased. Also the width of depletion layer of p-n junction decreases in forward bias.

A large increase in reverse voltage across p-n shows small increase in reverse current. Hence the resistance of p-n junction is high when reverse biased. Also the width of the depletion layer of p-n junction increases in reverse biased.

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