# assignemnt help

Discussion in 'Homework Help' started by UADV, Nov 22, 2012.

Nov 22, 2012
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hi all im on an electrical and electronics engineering course and and assignemnt to do, i was wondering if anyone could help me , in trying to find the formula or eqwuation need to find missing resistor value(s) , also could anyone explain how you do a mess circuit equation , i have most of it but when i look online throgh various forum and website the ending part is never explained so little lost can anyone help please thanks Jules

Nov 22, 2012
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sorry nearly forget to say this is for parallel circuit with a series resister

3. ### Audioguru Expert

Dec 20, 2007
10,668
1,190

Oh, you don't have a teacher but instead you are taught electronics by a robot?
Then ask the robot to explain Ohm's Law again to you.

Nov 22, 2012
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i understand Ohms laws I=V/R

5. ### Audioguru Expert

Dec 20, 2007
10,668
1,190
What is a "resister"? Is it a resistor with no value?

Why don't you post the detailed schematic then we will know what you are talking about?

Nov 22, 2012
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ok nps give me a few mins and i will try to explain properly with a schematic, all i ask is please dont give me the answer just give me to equation(s) its important to me that i learn this thank you

Nov 22, 2012
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the first circuit i need to find the missing values and the 2 i need to the a mesh anaylsis i believe

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8. ### Audioguru Expert

Dec 20, 2007
10,668
1,190
You do not need a formula. Instead you use common sense and simple grade 6 arithmatic.

9. ### WBahn Moderator

Mar 31, 2012
23,388
7,099
Okay, let's see if we can give you some real assistance here.

Let's focus on the first problem first, but even before we do that, consider the following:

You are trying to determine an unknown resistance.

Q1) What two peices of information directly related to that resistance do you need?
.
Our goal is to figure out those two peices of information for each unknown resistor.

So turning to the first circuit (Circuit 4):

Q2) What is the voltage on Node 2 (the node just to the left of R6) based only on the information provided by the left-most branch? Assume that the current meters are ideal (what does that mean?) or at least nearly so.

Q3) What is the voltage on Node 2 based just on the information provided by the second branch (the one with R2 in it)?

Q4) Are the answers to Q2 and Q3 consistent?

Q5) Based on the currents in the left two branches, what is the current through R6?

Q6) Based on the information in the third branch (the one with R3) what is the voltage on Node 3?

Q7) Based on the information in the right-most branch, what is the current in R5?

Q8) Based on the answers to Q6 and Q7, what is the voltage on Node 4?

Q9) Based on the currents in the right two branches, what is the current in R6? Is this consistent with the answer to Q5?

Q10) What are R5 and R6?

Answer these, in order, the best you can. Provide your reasoning, if possible. Then we can look your answers over and see what is right and what misconceptions or holes need to be addressed.

Q2) In

10. ### toffee_pie Senior Member

Oct 31, 2009
212
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i got the upper resistor @ 16k and the lower @ 29k

might be wrong. Rt = 8k

11. ### toffee_pie Senior Member

Oct 31, 2009
212
8
for the last node 22.5v = .75mA . (R4+R5)
we got R4 so R5 is 29k

probably wrong though

12. ### toffee_pie Senior Member

Oct 31, 2009
212
8
hmm
or maybe its 1k.....