The `V-I` characteristic of a silicon diode is shown in the Fig. 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 = 20 mA, V = 0.8 V, I = 10 mA, V = 0.7 V
`r_(fb) = DeltaV//DeltaI = 0.1V//10 mA = 10 Omega`
(b) From the curve at `V = –10 V, I = –1 muA,`
Therefore,
`r_(rb) = 10 V//1muA= 1.0 × 10^(7) Omega`