The document discusses n-p-n and p-n-p transistors, which are semiconductor devices that regulate current or voltage and function as switches for electronic signals. It explains the working principles of both types, detailing how charge carriers flow through the transistors under forward and reverse bias conditions. The presentation concludes with a summary of the key functions and behaviors of these transistor types.

1. Presentation topic
• n-p-n transistor
• p-n-p transistor and their working principle.

2. What is transistor
A transistor is a device that regulates current or voltage
flow and acts as a switch or gate for electronic signals.
Transistors consist of three layers of a semiconductor
material, each capable of carrying a current.

3. Types of transistor
Accordingly there are two types of transistor
1. n-p-n transistor
2. p-n-p transistor
n-p-n transistor: The npn transistor contains a thin p-region between two n-regions.
P-n-p transistor: The pnp bipolar transistor contains a thin n-region sandwiched
between two p-regions.

4. Introducing of transistor terminal

5. Working of npn transistor
The npn transistor with forward bias to emitter-base junction and reverse
bias to collector-base junction.The forward bias causes the electrons in n-
type emitter to flow towards the base.Only few electrons (less than 5%)
combine with holes to constitute base. More than 95% cross over into the
collector region.

6. Working of pnp transistor
The forward bias causes the holes in the p-type emitter to flow
towards the base. Only few holes less than 5% combine with the
electrons. The remainder more than 95% cross into the collector
region.

7. End of the presentation
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