Name: Common Base Configuration
Uploaded: 2019-07-19
Duration: 14 min 41 s
Description: Let's connect the battery to all three terminals of a transistor and understand the relation between the emitter current, base current and collector current.

Question

Explain with neat circuit diagram the working of an n-p-n transistor with brief description of its construction.

Accepted Answer

Working of an n-p-n transistor :

Here, the n-p-n transistor with forward bias to emitter base junction and reverse bias to collector base junction. The forward bias causes the electrons in the n-type emitter to flow towards the base constituting emitter current, $I_{e}$ .

As these electrons flow through the p-type base, they tend to combine with holes. As the base is lightly doped and very thin (around $\approx 1 μm$ ), only a few electrons (about $2 %$ ) combine with holes of the base and the atoms on receiving the electrons get negatively charged. The positive terminal of the battery $V_{e b}$ , attracts these electrons, forming base current $I_{b}$ and new holes in the base. The remaining (about $98 %$ ) electrons coming from the emitter cross over the base into the collector and they move under the reverse bias through the collector constituting collector current $I_{c}$ . It is clear that emitter current is the sum of collector and base currents i.e.

$I_{e} = I_{c} + I_{b}$

Explain with neat circuit diagram the working of an n-p-n transistor with brief description of its construction.

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