high voltage gain is obtained from CB configuration only.
because the input impedance is low and out impedance is
high in CB configuration. so we get maximum voltage gain in
CB. whereas for CE the input impedance is moderate and
output impedance is moderate. so we get maximum power gain
from CE. and CC voltage gain is approximately one. so this
will give maximum current gain. CC is used for impedance
matching. CC is also known as emitter follower. because of
its unity gain.
cb will have max voltate gain.
ce will have max power gain.
cc will have max current gain.
no doubt the maximum voltage gain will be obtained from CB
configuration only. for the answer 6: we dont connect any
resistors on either side of input and output. by its
connection we get input and output resistances. we know the
doping concentrations of emitter, base and collector.
depending upon the configuration we get input and output
impedences. nothing else.