In an n-p-n transistor, the majority carriers in the emitter and collector are :a)Free holesb)free electronsc)Free ionsd)Valence electronsCorrect answer is option 'B'. Can you explain this answer?

Question

Answer

Npn transistor is shown:
As we can see from the diagram, the emitter in the npn transistor is of n-type. Therefore majority charge carriers in the emitter of an npn transistor are called electrons

Answer

As we can see from the diagram, the emitter in the npn transistor is of n-type. Therefore majority charge carriers in the emitter of an npn transistor are called electrons.

Answer

The majority carriers in an n-p-n transistor are free electrons. To understand why this is the case, let's first understand how an n-p-n transistor works and the behavior of majority and minority carriers in the different regions of the transistor.

1. Transistor Basics:
- A transistor is a three-layer semiconductor device made up of two p-type regions (base and collector) sandwiched between an n-type region (emitter).
- The p-type region has an excess of holes (positive charge carriers), while the n-type region has an excess of electrons (negative charge carriers). This creates a p-n junction at the boundaries between the regions.

2. Behavior of Carriers in Different Regions:
- Emitter: In the emitter region, which is n-type, there is an excess of free electrons. These electrons are the majority carriers in this region.
- Base: The base region is p-type and has an excess of holes. These holes are the majority carriers in this region.
- Collector: The collector region is also p-type and has an excess of holes, making holes the majority carriers here.

3. Transistor Operation:
- When a small current is applied to the base-emitter junction, it allows the majority carriers (electrons in the n-type emitter and holes in the p-type base) to flow across the junction.
- This injection of electrons from the emitter into the base region forms the base current, and a larger current flows from the collector to the emitter, known as the collector current.
- The transistor acts as an amplifier, with a small input current controlling a larger output current.

4. Importance of Majority Carriers:
- In an n-p-n transistor, the majority carriers play a crucial role in the operation of the device.
- The electrons in the n-type emitter are the majority carriers responsible for the flow of current from the emitter to the base.
- Similarly, in the collector region, the holes are the majority carriers responsible for the flow of current from the base to the collector.

In conclusion, the majority carriers in an n-p-n transistor are free electrons in the emitter region and holes in the collector region. These carriers are responsible for the flow of current in the transistor and are crucial for its amplification function.

Similar Class 12 Doubts

When an n–p–n transistor is used as an amplifierthen [1996]

In a n-type semiconductor, which of the followingstatement is true? [NEET 2013]

Which of the statements is true for p-type semiconductors?

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