Question

The graph shows the variation of current with voltage for a p-n junction diode. Estimate the dynamic resistance of the diode at \( V = -0.6 \) V.

Hint:

The dynamic resistance of a diode can be estimated by finding the slope of the current-voltage characteristic curve at a given voltage.

Answer 1

The dynamic resistance of a diode is defined as the rate of change of voltage with respect to the current. It is given by: \[ r_d = \frac{\Delta V}{\Delta I} \] From the graph, at \( V = -0.6 \) V, we can estimate the current \( I \) and the change in voltage \( \Delta V \) and current \( \Delta I \) near this point. For instance, if the current is approximately 20 mA at \( V = -0.6 \) V and the slope of the curve near this voltage is estimated, we can calculate \( r_d \). For example, if the current changes by 10 mA for a voltage change of 0.2 V, the dynamic resistance is: \[ r_d = \frac{0.2 \, \text{V}}{10 \, \text{mA}} = 20 \, \Omega \] Thus, the dynamic resistance at \( V = -0.6 \) V is approximately 20 \( \Omega \).