I-V characteristics of four devices are shown in Fig. 15.1 Identify devices that can be used for modulation:

Question

Philoid · Accepted Answer

Only devices in which the current depends upon the square of the voltage can be used for modulation. Clearly, (i) and (iii) are linear graphs. Hence (a), (b) and (d) are incorrect. Also, note that some region of (iv) is quadratic and hence, can be used for modulation. Thus, option (c) is correct.