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Transistors
Well, as mentioned earlier, what happens in one of the two
PN junctions of the transistor affects the other. Let’s say for
example that we start the lower PN junction (between base
and emitter) conducting by raising the base voltage so that
the base-to-emitter voltage is above the transition voltage of
the junction (say, 0V6 if the transistor is a silicon variety).
Figure 8.5 shows this situation. Now, the lower junction is
flooded with charge carriers and because both junctions are
very close together, these charge carriers allow current flow
from collector to emitter also, as shown in Figure 8.6.
Figure 8.5
If the voltage at the base is raised, current flows from base to emitter
Figure 8.6 Charge carriers accumulating around the lower junction allow
current to flow from the collector to the emitter
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