Question

The graph of $I-V$ characteristics of a $p-n$ junction diode is shown below. If the diode is connected to a signal generator of peak voltage $22\, V$, then the de current across the load of $4.8\, \Omega$ will be _________A.
(Take $\pi=22 / 7$ )

Answer 1

The current at $2 V$ is $250\, mA$ and at $2.2\, V$ it is $500\, mA$.
The dynamic resistance in this region is,
$r_{d} =\frac{\Delta V}{\Delta I}$
$=\frac{(2.2-2)}{(500-250) \times 10^{-3}}=\frac{4}{5} \Omega$
Now, when the diode is connected to ac supply it works as a half-wave rectifier giving a dc output. For half-wave rectifier, peak current is,
$I _{0} =\frac{ V _{0}}{ r _{ d }+ R _{ L }}$
$=\frac{22}{\frac{4}{5}+4.8}$
$=\frac{22}{5.6} A$
$\therefore I_{d c}=\frac{I_{0}}{\pi}=\frac{22}{5.6 \times \frac{22}{7}}$
$=\frac{5}{4}$
$=1.25\, A$