I can't come up with the solution the book provides for problem 10-13 in the image below. This requires completing 10-12 also, which I don't have a solution for. I think I'm getting hung up on the common ground connections and how the circuit should be rearranged after short circuiting Vt

remove RL and determine Va-b. Each parallel branch should be 60v, using voltage divider for R2-3 I come up with Va-b=36v
Then I short circuit Vt and find the circuit equivalent resistance. With the common ground and short circuited Vt, R1 & R2 are in series and combine to equal R1-2=2kohm. R2-3||R3 = 857ohm (unusual answer for this book tells me I'm wrong). Using 36V and 857ohms I get IL=17mA and VL= 15V (both wrong)




Answer is RL=1200ohm, IL=20mA, VL=24v

Moderators note : turned picture upright. How difficult is that for you to do?

 

When Vt is shorted (zero the source), doesn't that also short-circuit R1?

 

Take a step back and do 10-12 and show it. That should make things more obvious and, if not, allow us to point some things out better.

 

When Vt is shorted (zero the source), doesn't that also short-circuit R1?

Yes, it does.

 

Take a step back and do 10-12 and show it. That should make things more obvious and, if not, allow us to point some things out better.

This is my wrong answer with work

 

In post #1 you said that Vab is 36 volts, but in your work you have 24 volts; why the difference?

Also, it has already been pointed out to you that when you short the 60 volt source, you also short R1. That means that R1 shouldn't be included in any calculations to find Rth.

Fix these errors and try again.

 

Hi please see attached.

I think you got it wrong guys.

 

Vth = 36V
Rth = 0.6kOhms

 

Vth = 36V
Rth = 0.6kOhms

Thank you for the input, the short circuit was my problem.

Sorry about the sideways pictures, I selected the rotate button when posting and nothing happened

 

Hi please see attached.

I think you got it wrong guys.

Do NOT work a member's homework for them. This is Homework Help, not Homework Done For You. The goal is to GUIDE the member into solving their own problems. Figure that they've likely seen several example problems worked, both in the text and in class, and something hasn't quite clicked. Seeing someone else work yet one more problem is unlikely to magically change that. The more likely outcome is that they will THINK they've got it figured out and discover that they don't the next time they see a similar problem on the exam.

 

Thank you for the input, the short circuit was my problem.

Which is what everyone has been telling you.

 

Do NOT work a member's homework for them. This is Homework Help, not Homework Done For You. The goal is to GUIDE the member into solving their own problems. Figure that they've likely seen several example problems worked, both in the text and in class, and something hasn't quite clicked. Seeing someone else work yet one more problem is unlikely to magically change that. The more likely outcome is that they will THINK they've got it figured out and discover that they don't the next time they see a similar problem on the exam.

Got it