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Junction Transistors — Revision Notes

ICSE · Class 12 · Physics

Junction Transistors revision notes for ICSE Class 12 Physics: 4 topics in quick points. Key terms: A p, The emitter supplies majority and In a p.

53 questions35 flashcards7 formulas & key relations5 concepts

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Key Topics to Revise

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1. Basic idea of a junction transistor

  • A junction transistor has three regions: emitter, base, and collector.
  • It is formed by sandwiching a thin layer of doped semiconductor between two thick similar layers of opposite type.
  • There are two types of junction transistors: p-n-p and n-p-n.
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2. Types of transistors and symbol directions

  • In a p-n-p transistor, a thin n-type base is sandwiched between two p-type blocks.
  • In a n-p-n transistor, a thin p-type base is sandwiched between two n-type blocks.
  • For p-n-p, the emitter is positive and the collector is negative with respect to the base.
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3. Transistor action and current relation

  • In transistor action, the emitter-base junction is forward biased and the base-collector junction is reverse biased.
  • In a p-n-p transistor, holes move from emitter to base and most of them pass to the collector.
  • About 98% of holes entering the base from the emitter pass to the collector, while about 2% combine with electrons in the base.
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4. Current gain and related parameters

  • Direct current gain in common-base configuration is collector current divided by emitter current.
  • Alpha for common transistors ranges from 0.95 to 0.98, with limiting value 1.
  • Current gain in common-emitter configuration is beta.

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Full Notes

Key Concepts

A pThe emitter supplies majority carriersIn a pIn an nIn a p

Frequently Asked Questions

What are the important topics in Junction Transistors for ICSE Class 12 Physics?
Key topics in Junction Transistors include Basic idea of a junction transistor, Types of transistors and symbol directions, Transistor action and current relation, Current gain and related parameters. Study these first, then practise questions on each for the ICSE Class 12 board exam.
How should I revise Junction Transistors for the ICSE Class 12 board exam?
Learn the core ideas first, then work through the 53 practice questions on Junction Transistors. Revise definitions regularly and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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