Question 512 Marks
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) $V_D=-10 V$.
Answer
View full question & answer→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 $I=20 mA , V=0.8 V ; I=10 mA , V=0.7 V$ $r_{f b}=\Delta V / \Delta I=0.1 V / 10 mA =10 \Omega$
(b) From the curve at $V =-10 V , I=-1 \mu A$, Therefore,
$
r_{r b}=10 V / 1 \mu A =1.0 \times 10^7 \Omega
$
(a) From the curve, at $I=20 mA , V=0.8 V ; I=10 mA , V=0.7 V$ $r_{f b}=\Delta V / \Delta I=0.1 V / 10 mA =10 \Omega$
(b) From the curve at $V =-10 V , I=-1 \mu A$, Therefore,
$
r_{r b}=10 V / 1 \mu A =1.0 \times 10^7 \Omega
$