npn transistors are preferred to pnp transistors because they have

Options

A. low cost
B. low dissipation energy
C. capable of handling large power
D. electrons have high mobility than holes and hence high mobility of energy

Answer

To understand why NPN transistors are preferred over PNP transistors, we can analyze the key characteristics and properties of both types of transistors step by step.

### Step-by-Step Solution:

1. **Understanding Transistor Types**:
- NPN and PNP transistors are two types of bipolar junction transistors (BJTs). In an NPN transistor, the majority charge carriers are electrons, while in a PNP transistor, the majority charge carriers are holes.

2. **Charge Carrier Mobility**:
- Electrons (in NPN transistors) have higher mobility compared to holes (in PNP transistors). This means that electrons can move through the semiconductor material more easily and quickly than holes can.

3. **Current Flow**:
- In an NPN transistor, when a small current flows into the base, it allows a larger current to flow from the collector to the emitter. The high mobility of electrons facilitates this process, leading to efficient current amplification.

4. **Efficiency and Power Handling**:
- Due to the higher mobility of electrons, NPN transistors can handle larger currents and dissipate power more efficiently than PNP transistors. This makes them more suitable for high-speed and high-power applications.

5. **Cost and Dissipation**:
- The cost of NPN and PNP transistors is generally similar, and the energy dissipation characteristics are also comparable. Therefore, these factors do not significantly influence the preference for NPN over PNP transistors.

6. **Conclusion**:
- The primary reason NPN transistors are preferred over PNP transistors is that electrons have higher mobility than holes, which allows for better performance in terms of speed and efficiency in electronic circuits.

### Final Answer:
NPN transistors are preferred to PNP transistors because electrons have high mobility than holes, leading to better performance and efficiency in electronic applications.