Need help with diode equation :(

unclebehrooz

Joined Oct 1, 2012
2
Our Professor asked me to prove the equation of dynamic resistance of diode , he want me to explain him where did the equation come from !

The equation is this : $$r_AC{}$$ = n . $$V_T{}$$ / $$I_Q{}$$

$$r_AC{}$$ is dynmic resistance
$$V_T{}$$ stands for thermal voltage
$$I_Q{}$$ is the I at the operating point of diode