Kirchhoff's Voltage Law - Closed Loop?

[JJBladester]

Homework Statement

Determine V_C for the network in Fig. 7.24 (left-hand image).

Homework Equations

Kirchhoff's Voltage Law: The algebraic sum of the potential rises and drops around a closed path (or closed loop) is zero.

The Attempt at a Solution

This is an example problem in my book "Introductory Circuit Analysis" by Boylestad, 12th Ed., page 256. I understood KVL in the chapter on series dc circuits. There, closed loops were obvious.

My hangup with this question is I don't see how Fig. 7.25 represents a closed loop.

The book states:

$$V_{C}+V_{R_C}-V_{CC}=0$$

Why are we subtracting V_CC?

Can somebody post a Microsoft Paint drawing to show me how Fig. 7.25 is a closed loop?

 

[ehild]

Look at the closed loops. They did not draw the battery, but it is there!

ehild

 

[JJBladester]

Look at the closed loops. They did not draw the battery, but it is there!

ehild

People like you are what make this site among the best on the 'net. You responded within minutes of my OP. Thank you.

So is there a rule of thumb that I can use when I run into this dilemma? What about the circuit told you that the battery was definitely hooked up as in your image? I mean, it would be feasible to draw the battery into the circuit a different way (as in below) and get a different result, right?

 

[ehild]

Your circuit is different from the original one. The emf of your battery is 2 V, Vcc =22 V can not be supplied with such an arrangement, without an additional battery.
The potential must be 22 V at the point shown with respect to the ground, which is at zero potential. That is the maximum potential shown: there must be a battery with that emf.
The real transistor circuits have some supply voltage, a battery. That is what I drew. The Base voltage is obtained by the voltage divider R1 and R2 in series. I know it because I have made a lot of such circuits...

ehild

 

[JJBladester]

OK, now I see it...

The branch you added to the left was there to begin with and it is the long-hand way of drawing in V_CC. Correct?

 

[ehild]

I do not know what long-hand way is, but the battery was there. Maybe, not really a battery, but some other appliance for power supply: transformer connected to 230 V ac, with rectifier and stabiliser and so on, with output 22 V dc.

ehild