(i) [Note : For diagram see Ans. L.A.T.Q. 2(a)] For input characteristics :
At constant VCE, for different values of VCB, the different values of IB are obtained.
At constant IB, for different values of VCE, the different values of IC are obtained.
(ii) A portion of output power is returned at the input in same phase as that of starting power; hence the output in the oscillator gets self sustained. This is termed as positive feedback.
As the switch S1 is closed, a sugar of collector current flows through coil T2, which causes a changing magnetic flux around it. Hence a portion of the output G fed, back to the coil T1 , as a result of the positive feedback The emitter current, therefore, starts oscillation.