draw the circuit diagram to determine the characteristics of a PNP transistor in common emitter configuration.explain ,using I-V characteristics how the collecter current changes with the base current.how can.1)output resistance 2) current amplicataion factor be determined from the I-V characters
Answers
The PNP transitor is designed for negative power source which is caused by negative base and collector current. This is the opposite of NPN transistor.
The property or the behaviour of PNP transistor is controlled by current flowing out of the base terminal. The collector current (Ic) does not depend on the voltage across collector emitter terminal (Vce), but depends on base current (Iv).
Usually, more voltage causes more current. But here, the current increases with the increasing of negative voltage across collector emitter terminal (Vce).
The characteristic curve (shown in Fig. 2.) of PNP transistor are a set of flat and evenly spaced lines. Each flat line shows that collector current (Ic) does not change for changing voltage of collect emitter terminal (Vce). Thus the graph (Fig.2) shows the collector current (Ic) does depend on base current (Iv).
We can define amplification factor of PNP transistor as the ratio of collector current (Ic) to the base current (Iv). It is denoted as β where
β = Ic/Iv
Ic = β.Iv ... equation 1
*Here, we can see, in Equation 1. the collector current (Ic) depends on base current (Iv). They are proportional to each other. (Number 2 answer)
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From Ohm's Law, we can say, V = IR or, R = V/I
So, we can say, in PNP transistor, the output resistance is ratio of collector emitter voltage (Vce) to the collector current (Ic).
Thus, output resistance (Ro) = Vce/Ic (Number 1 answer)
