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Urgent Circuit Analysis (Req in Parallel and Series)

  • Engineering
  • Thread starter planauts
  • Start date
86
0
1. Homework Statement
http://puu.sh/1faG5 [Broken]


2. Homework Equations



3. The Attempt at a Solution
http://puu.sh/1faFD [Broken]

I labelled the nodes ^^.

I redrew the circuit based on the nodes, I ignored the 10 ohm resistor because it short circuits. (Note: I drew the series resistors in reverse order, 80 ohms should be between Node A and Node B, instead, I drew it between B&C. However, the result should be the same.)

http://puu.sh/1faFh [Broken]
Based on this, the resistance is:
20 || 30 || (80+8)

Req = 10.56 ohms.

But that is not the answer, I'm not sure where I am going wrong, could someone please help me out please. Thanks a lot! Exam tomorrow :(
 
Last edited by a moderator:

Answers and Replies

gneill
Mentor
20,536
2,626
In your second drawing you have NODE C directly connected to terminal B. This is not how it is in the original drawing. I think you need to think a little more about how to redraw the circuit so that all the nodes and connections are preserved.

Eliminating the 10k resistor is fine; as you say, it's shorted out. The same short puts the top of the 20k resistor in contact with the bottom of the 30k resistor...
 
86
0
I got 16 kilo-Ohms, I think I understand what mistake I made now. I didn't follow the current from the negative terminal, I was just trying to make them connect. Makes sense now. :) THanks
 

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