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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 Circuits3 Marks
Question
  1. In the following diagram ‘S’ is a semiconductor. Would you increase or decrease the value of R to keep the reading of the ammeter A constant when S is heated? Give reason for your answer.
  1. Draw the circuit diagram of a photodiode and explain its working. Draw its I - V characteristics.
✓

Answer

  1. R would be increased.
Resistance of S (a semi conductor) decreases on heating.
  1. Photodiode diagram:

When the photodiode is illuminated with light (photons) (with energy (hv) greater than the energy gap (Eg) of the semiconductor), then electron-hole pairs are generated due to the absorption of photons. Due to junction field, electrons and holes are separated before they recombine. Electrons are collected on n-side and holes are collected on p-side giving rise to an emf. When an external load is connected, current flows.
V-I Characteristics of the diode:

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