Match electronic components to predominant noise types: (A) Resistance, (B) Diode, (C) Triode, (D) p–n junction — with: (1) current noise, (2) partition noise, (3) shot noise, (4) atmospheric noise, (5) Johnson (thermal) noise.
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AA-5, B-3, C-2, D-1
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BA-1, B-2, C-3, D-5
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CA-3, B-5, C-1, D-2
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DA-3, B-5, C-2, D-1
Answer
Correct Answer: A-5, B-3, C-2, D-1
Explanation
Introduction / Context:Recognizing dominant noise mechanisms is key for low-noise design. Thermal agitation in resistors, discrete charge flow in junctions, and carrier partition in multi-electrode devices create distinct spectral behaviors that affect receivers and amplifiers across RF and audio bands.
Given Data / Assumptions:
- Resistor noise is thermal (Johnson noise).
- Diode junctions exhibit shot noise due to discrete charge carriers traversing a barrier.
- Vacuum triodes exhibit partition noise from electron stream division among electrodes.
- p–n junctions can exhibit current-related (shot/flicker) noise; here 'current noise' is the remaining classified term to pair.
Concept / Approach:Map each device to the noise it is most classically associated with in exam syllabi: Johnson noise ↔ resistors; shot noise ↔ diodes; partition noise ↔ multi-electrode tubes; current noise ↔ semiconductor junction conduction fluctuations.
Step-by-Step Solution:
A (Resistance) → Johnson (thermal) noise → 5.B (Diode) → shot noise from discrete charge arrivals → 3.C (Triode) → partition noise in electron stream → 2.D (p–n junction) → categorized here as current noise → 1.Verification / Alternative check:Spectral traits: thermal noise ~ kTB across resistors; shot noise current ~ 2qI*B in junctions; partition noise arises where carriers split among paths (e.g., triodes).
Why Other Options Are Wrong:
- A-1, B-2, C-3, D-5: Misplaces thermal and shot noise pairings.
- A-3, B-5, C-1, D-2: Assigns shot noise to resistors, which is incorrect.
- A-3, B-5, C-2, D-1: Gives diodes thermal noise as dominant, which is not typical.
Common Pitfalls:
- Confusing thermal noise (present in any resistance) with shot noise (junctions).
- Assuming atmospheric noise originates in components; it is an external interference source.
Final Answer:A-5, B-3, C-2, D-1