Understanding transistor circuits

saturationtransistors

I have been working my way through The Art of Electronics by Horowitz and Hill and I've just started the chapter on Transistors. I am having some difficulty in understanding this transistor circuit:

enter image description here

The text explains that "When the switch is closed, the base
rises to 0.6 volt (base-emitter diode is in
forward conduction). The drop across
the base resistor is 9.4 volts, so the base
current is 9.4mA." What I don't understand is why the voltage drop across the base resistor is 9.4 volts? Surely the voltage across the resistor should be 10 volts (0.01 amps times 1000 ohms) and this would mean that the entirety of the source voltage is dropped?

The text also mentions that this is an example of transistor saturation.

Many Thanks in advance

Best Answer

Here are the voltages as they are described:

enter image description here

Now, if you want to calculate the resistor current, you can see that it is 9.4V / 1000-Ohm = 9.4 mA. Since the base is in series with the resistor, the resistor current = the base current.

Does this help?