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Junction Transistors

ICSE · Class 12 · Physics

Quick revision notes for Junction Transistors — ICSE Class 12 Physics. Key concepts, formulas, and definitions for last-minute revision.

53 questions35 flashcards5 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?
Junction Transistors covers several key topics that are frequently asked in ICSE Class 12 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.
How to score full marks in Junction Transistors — ICSE Class 12 Physics?
Understand the core concepts first, then work through the 53 practice questions available for this chapter. Revise formulas and 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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