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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: In a semiconductor diode, the reverse biased current is due to drift of free electrons and holes.
Reason: The drift of electrons and holes is due to thermal excitation.
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Answer

  1. Both A and R are true but R is not the correct explanation of A.

Explanation:

A reverse bias on a p-n junction opposes the movement of the majority charge carriers thus stopping the diffusion current. It makes the free electrons and holes to drift cross the junction. Therefore a small current in $\mu\text{A}$ flows even when the p-n junction is reverse biased. The drift current is due to the thermal excitations of the electrons and holes.

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