Draw the typical input and output characteristics of an n-p-n transistor in CE configuration. Show how these characteristics can be used to determine (a) the input resistance (r ), and (b) current amplification factor (β)

The input and output characteristics, of a n-p-n transistor, in its CE configuration, are as
shown.


Input resistance

${\mathrm{r}}_{\mathrm{i}}={\left(\frac{{\mathrm{\Delta V}}_{\mathrm{BE}}}{{\mathrm{\Delta I}}_{\mathrm{B}}}\right)}_{{\mathrm{V}}_{\mathrm{CE}}}$

The relevant values can be read from the input characteristics.
Current amplification factor
$\mathrm{\beta }={\mathrm{\Delta I}}_{\mathrm{C}}/{\mathrm{\Delta I}}_{\mathrm{B}}$

The relevant values can be read from the output characteristics,
corresponding to a given value of 𝑉_𝑪𝑬.