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Transistor (NPN Idea)
An NPN transistor has base, collector and emitter terminals. A small base input controls a larger collector-emitter current for switching or amplification.
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Transistor (NPN Idea)
A transistor works like an electronic control switch.
A small signal at one terminal can control a larger current elsewhere in the circuit.
Recommended for Class 10
Transistor (NPN Idea)
A transistor is a semiconductor device used to control electrical signals and current.
An NPN transistor has three terminals:
Emitter (E) Base (B) Collector (C)
A relatively small change in the base input can control a much larger collector-emitter current.
This property allows a transistor to be used as:
an electronic switch; an amplifier.
Basic Idea
The base acts as the control terminal.
A suitable small base signal allows a larger current to flow through the collector-emitter path.
Transistor (NPN Idea) — Advanced
In a bipolar junction transistor, a small base-emitter input controls carrier flow through the collector-emitter circuit, enabling switching and amplification.
Common Mistakes
Common Mistakes
- Mistake
Mistake: A transistor creates electrical energy. Correction: It uses a small input signal to control energy supplied by the circuit's power source.
Revision Zone
60-Second Revision
Quick cues from this topic — use them for last-minute revision.
NPN transistor → B, C, E.
Small base signal → controls larger current.
Uses → switching + amplification.
- Definition
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Practice
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Q1. Name terminals.
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Q2. Describe base role.
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Q3. State two uses.
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Q4. Explain small-signal control.
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Q5. Explain why transistor does not create energy.
Exam Practice
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Q1. Define transistor.
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Q2. Name NPN terminals.
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Q3. Explain transistor as control device.
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Q4. Give two uses.
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Q5. Explain the role of base signal.
School-standard facts for Matric and Intermediate. Original explanations — not copied from textbooks.