Question

If $x,y$ and $z$ are the lengths of the emitter, base and collector of a transistor respectively then:

• A. $z<x<y$
• B. $z>x>y$
• C. $z<y<x$
• D. $x=y=z$

Answer 1

The correct option is B $z>x>y$

In a transistor,

$\text{Area of collector > area of emitter > area of base}$ for proper collection of majority charge carriers.

As the collector is meant for collecting all the moving charge carriers, the collection process involves dissipation of heat from the charge carriers. In order to dissipate the heat, collector is made with large surface area, which makes collector the larger than base and emitter.

The length of the base is small to avoid the acculartion of charge in this region.

Hence, $\left(B\right)$ is the correct answer.