Semiconductor Electronics
p-n junction, transistors, logic gates, communication
Key Concepts
- Semiconductors: conductivity between conductors and insulators; increases with temperature
- p-n junction diode: forward bias conducts, reverse bias blocks
- Zener diode: operates in reverse breakdown — used as voltage regulator
- Transistors (BJT): NPN or PNP; used as switches and amplifiers
- Logic gates: AND, OR, NOT, NAND (universal), NOR (universal)
Important Formulae
| Current in transistor | I_E = I_B + I_C |
| Current gain (β) | β = I_C / I_B |
| Current gain (α) | α = I_C / I_E = β/(1+β) |
| Half-wave rectifier output | V_dc = V_max / π |
| Full-wave rectifier output | V_dc = 2V_max / π |
Quick Tips
- V_BE ≈ 0.7 V for Silicon, 0.3 V for Germanium in forward bias.
- NAND and NOR gates are universal — any logic function can be built from them alone.
- Intrinsic semiconductor: n_e = n_h; donor impurity increases electrons (n-type); acceptor increases holes (p-type).
Sample Practice Questions
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In a full-wave rectifier with centre-tap transformer, output frequency:
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Answer: Double the input frequency
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In a p-type semiconductor, acceptor impurities create:
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Answer: Holes as majority carriers
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Zener diode is used as:
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Answer: Voltage regulator
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Silicon has band gap of approximately:
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Answer: 1.1 eV
Practice Questions
Practice 20 randomly selected NEET questions on Semiconductor Electronics. Answers are revealed after each question.
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What are the key concepts in Semiconductor Electronics for NEET?
Semiconductors: conductivity between conductors and insulators; increases with temperature; p-n junction diode: forward bias conducts, reverse bias blocks; Zener diode: operates in reverse breakdown — used as voltage regulator; Transistors (BJT): NPN or PNP; used as switches and amplifiers; Logic gates: AND, OR, NOT, NAND (universal), NOR (universal).
Which formulae are important for Semiconductor Electronics in NEET?
Current in transistor: I_E = I_B + I_C; Current gain (β): β = I_C / I_B; Current gain (α): α = I_C / I_E = β/(1+β); Half-wave rectifier output: V_dc = V_max / π; Full-wave rectifier output: V_dc = 2V_max / π.
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