For the forward biased diode characteristics shown in the figure,
Question:

For the forward biased diode characteristics shown in the figure, the dynamic resistance at $\mathrm{I}_{\mathrm{D}}=3 \mathrm{~mA}$ will be_____$\Omega .$

Solution:

$\mathrm{R}_{\mathrm{d}}=\frac{\mathrm{dV}}{\mathrm{di}}=\frac{1}{\frac{\mathrm{di}}{\mathrm{dv}}}=\frac{1}{\frac{5-1 \times 10^{-3}}{0.75-0.65}}$

$\frac{100}{4}=25 \Omega$