Thank you very much Studiot for theoretical and practical explanations together with nice illustrations. I also thank Danijel for treating the question from other aspects.
To Studiot:
Why does the author call “floating point” specifically only the cases of Figs 4-49a and 4-44? As far as I understand, the ground is floating ground ,which isn’t connected to Earth. In this case, aren’t all voltages measured floating, Vcc or Vbb?
In your statement “In theory the voltage at the base is indeterminate since it is not connected to anything. (In theory it is totally isolated from the base and emitter by the internal structure of the transistor.)” Shouldn’t it be “… from the collector and emitter…”?
So, based on this explanation of yours, in the non-conducting state of the transistor, I understand that all the leads can approximately be considered as separated parts not touching each other. Am I right?
I would like to ask a general question: If we consider a transistor as being consisted of internal resistors (internal resistances between collector, base and emitter), would the voltages measured be like those in true resistors? For example, would the measured voltages on points between collector and base be between 9V and 3V?
To Danijel: In your statements:
“We could debate this. It might actually be higher than with the connected voltmeter (but certainly below some 0.5V). In any case it is quite floating and so who cares...”, what do you mean by some 0.5V? Also, what do you mean by “In any case it is quite floating and so who cares...”?
“Regarding the picture 4-44 in the OP, I think the book might be partially in error. Depending on the voltage supplied at the transistor base, the voltage at the collector lead might be higher than few mV. It is actually similar to the 4-39f case.” In this case, the collector lead is also grounded like the emitter lead by multimeter ground. Is this is the reason why more than a few mV?
“…The base-emiter junction voltage rises up slightly so that the system reaches equilibrium…” Could you clear up this for me please?