The V-I characteristic of a silicon diode is shown in the Fig. 14.17. Calculate the resistance of the diode at (a) `I_(D) = 15 mA" and "(b) V_(D) = –10 V`.

Explanation

Considering the diode characteristics as a straight line between I = 10 mA to I = 20 mA passing through the origin, we can calculate the resistance using Ohm.s law.
a) From the curve, at `I=20A, V=0.8V`,
`I=10mA, V=0.7V`
`r_("fb")=DeltaV//DeltaI=0.1V//10mA=10Omega`
b) From the curve at `V=-10V.I=-1muA`.
Therefore, `r_("rb")=10V//1muA=1.0xx10^(7)Omega`