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Zorluk: OrtaTransistors

An electronics technician is troubleshooting an NPN bipolar junction transistor (BJT) configured as a solid-state switch. To transition the transistor from the cutoff state into saturation to energize an attached load, which electrical condition must be established at the base-emitter junction?

  1. A
    Reverse-biasing the base-emitter junction by making the base negative with respect to the emitter
  2. Forward-biasing the base-emitter junction by applying a positive voltage to the base relative to the emitterCevap
  3. C
    Maintaining zero volts across the base-emitter junction while reverse-biasing the collector-base junction
  4. D
    Applying a negative voltage to the collector while drawing conventional current out of the base terminal

Cevap

Forward-biasing the base-emitter junction by applying a positive voltage to the base relative to the emitter causes the NPN transistor to transition into saturation.
In an NPN bipolar junction transistor, the base is composed of P-type semiconductor material while the emitter is N-type. To turn the transistor ON and enter saturation, the base-emitter junction must be forward-biased with a positive base voltage that exceeds the silicon barrier potential (≈0.7 V\approx 0.7\text{ V}). This introduces base current, which allows heavy electron flow from emitter to collector, effectively closing the circuit across the load.

Adım Adım Çözüm

1
Identify the semiconductor structure and terminal polarities for an NPN transistor.
An NPN bipolar junction transistor consists of an N-type emitter, a thin P-type base, and an N-type collector.
Understanding component internal structure determines the required polarity for current control.
2
Determine the required junction biasing to turn the transistor ON.
The base-emitter (P-N) junction must be forward-biased by establishing a base potential approximately 0.7 V0.7\text{ V} higher than the emitter.
Forward bias reduces the depletion region barrier, allowing majority carriers to flow across the junction.
3
Analyze the conditions necessary to reach the saturation operating state.
Supplying sufficient forward base current drives the collector-emitter voltage (VCEV_{CE}) to its minimum near 0.2 V0.2\text{ V}, acting as a closed switch.
Saturation occurs when maximum collector current flows, turning the solid-state switch fully ON to power the load.

Anahtar Kavram

Transistor Biasing and Solid-State Switching States
Tahmini Süre:1m 0s
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Transistors

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