CBSE Class 12 · 2016 · Delhi · SemiconductorsShort Answer

(a) The emitter is heavily doped and supplies the majority charge carriers; the base is thin and lightly doped and controls the fraction of carriers reaching the collector; the collector is moderately doped and larger in size, and collects the carriers.
(b) Connect the n-p-n transistor in CE configuration with a source $V_{BB}$ (with a resistor) for the base and $V_{CC}$ for the collector, and meters to read $I_B$, $V_{BE}$, $I_C$ and $V_{CE}$.
Input characteristic: keep $V_{CE}$ fixed and plot $I_B$ against $V_{BE}$.
Output characteristic: keep $I_B$ fixed and plot $I_C$ against $V_{CE}$, repeating for several values of $I_B$.
$\boxed{\text{Input: }{I}_B\text{-}{V}_{BE}(V_{CE}\text{ fixed});\text{Output: }{I}_C\text{-}{V}_{CE}(I_B\text{ fixed}).}$