Question 2
AIM: To determine the input characteristics of a transistor in common emitter configuration.

1.   Connect the circuit as shown in Fig. 2.
2.   Ask the supervisor to check the circuit connection.
3.   Copy Table 2 into your answer booklet.

Table 2

IB (	VBE (V)
10
20
30
40
50
60

1.   Close switches S1 and S2.
2.   Set the collector-emitter voltage (V2) to 3 V.
3.   Adjust the input voltage (V1) until the ammeter reads 10 .
4.   Measure and record in Table 2, the corresponding base emitter voltage (VBE).
5.   Repeat steps (f) and (g) for other values of IB in Table 2.
6.   Open switches S1 and S2.
7.   Plot a graph of IB ( on the vertical axis against VBE (V) on the horizontal axis.
8.   Calculate the slope of the graph.
9.   Comment briefly on the slope of the graph.

The candidates were expected to connect the circuit as shown in Fig. 2, measure and record in Table 2 the expected VBE (V) readings. They were also required to plot a graph of IB ( against VBE (V), calculate the slope and comment briefly on it.
The expected answers were:
 (c)                                           Table 2
           

IB()	VBE(V)
10	0.50 – 0.65
20	0.50 – 0.65
30	0.50 – 0.65
40	0.50 – 0.65
50	0.50 – 0.65
60	0.50 – 0.65

                 As reported, majority of the candidates who attempted this question did very well.