#### Consider a box with three terminals on top of it as shown in Fig.14.18 (a): Three components namely, two germanium diodes and one resistor are connected across these three terminals in some arrangement. A student performs an experiment in which any two of these three terminals are connected in the circuit shown in Fig. 14.18 (b). The student obtains graphs of current-voltage characteristics for unknown combination of components between the two terminals connected in the circuit. The graphs are (i) when A is positive and B is negative (ii) when A is negative and B is positive (iii) When B is negative and C is positive (iv) When B is positive and C is negative (v) When A is positive and C is negative (vi) When A is negative and C is positive From these graphs of current – voltage characteristic shown in Fig. 14.18 (c) to (h), determine the arrangement of components between A, B and C.

a) n-side of the PN junction is connected to the A terminals while B is connected to the top-side of PN junction.

b) the knee voltage is 0.7V.

c) C is connected to the PN junction and n-side of the junction is connected to the B terminal, and knee voltage is 0.7V.

d) This above condition explains the connection between pn-junction with I and II with the resistance.