I've been trying to crack this all day. We we're giving a complex circuit for the 1st time without them completely being all resistors. The furthest I have gotten is finding total amps and resistance. I found total amps by determining lines 1-4 are in series with line 5 and in series ampage is constant. Line 5 had the given ampage of 5a which means 1-4 is also 5a which also means total ampage is 5a. With total voltage and ampage I got a total of 13ohms. After that I'm lost. I'm not even sure if I did that part completely right. Any ideas on how to go deeper into the problem? Please and thank you

 

Welcome to AAC!

A right reading schematic for convenience:


Is the value for R1 (3Ω) correct? It doesn't make sense to me.

EDIT: And I assume the wire across R1 and R2 is a mistake.

 

Welcome to AAC!

Do you know Kirchhoff's Voltage and Current Laws?

 

Welcome to AAC!

A right reading schematic for convenience:
View attachment 164739

Is the value for R1 (3Ω) correct? It doesn't make sense to me.

EDIT: And I assume the wire across R1 and R2 is a mistake.

Yeah that's the exact problem he gave us. R1 is 3ohms. And yes that wire through 1 and 2 was supposed to be erased, sorry

 

Yeah that's the exact problem he gave us. R1 is 3ohms. And yes that wire through 1 and 2 was supposed to be erased, sorry

You have enough information to solve for R1. Do it and see if you think it makes any sense.

 

You have enough information to solve for R1. Do it and see if you think it makes any sense.

Ok I'll focus on that and come back with an update

 

Meant to say I1, but can't correct because you've quoted it.

 

You say that the problem isn't all resistors and yet you show a problem with five resistors. Are these five impedances (with Z1 being 3 Ω)?

Are the currents and voltages magnitudes?

I don't think there's enough information to solve it since each unknown component has two unknown values associated with it (the real and the imaginary).

But if you assume that all of the components ARE resistors, the solution drops out almost by inspection. Are you sure that this is a complex circuit and not purely resistive?

 

You say that the problem isn't all resistors and yet you show a problem with five resistors. Are these five impedances (with Z1 being 3 Ω)?

Are the currents and voltages magnitudes?

I don't think there's enough information to solve it since each unknown component has two unknown values associated with it (the real and the imaginary).

But if you assume that all of the components ARE resistors, the solution drops out almost by inspection. Are you sure that this is a complex circuit and not purely resistive?

I feel the professor made a complex circuit with 5 resistors that each had an ohmic value, calulated the ohm total voltage total and ampage total and with that figured out volts 1-5 and amps 1-5 (which I am fully capable of doing). I feel like after he got those values he just erased most of the values he found and said figure out the missing ones

 

I feel the professor made a complex circuit with 5 resistors that each had an ohmic value, calulated the ohm total voltage total and ampage total and with that figured out volts 1-5 and amps 1-5 (which I am fully capable of doing). I feel like after he got those values he just erased most of the values he found and said figure out the missing ones

Okay, I get it. You meant "complex" in the usual English since of "not simple" instead of the circuits-analysis sense of "resistive and reactive components described by complex numbers".

Can you write down the voltage on each node (using 0 V as the bottom-left node)?

Once you have that, can you find the unknown currents in any of the branches?

Once you have that, can you figure out any more of the values (currents or resistances)?

Each time you find one value, it becomes easier to find another value.

 

I am not sure that there is a unique solution.
Nevertheless, you stated that the symbols may not all be resistors.
There are missing voltage or current sources in the picture.
I am not going to reveal the solution at this point. See what you can discover at this point.

 

I am not sure that there is a unique solution.
Nevertheless, you stated that the symbols may not all be resistors.
There are missing voltage or current sources in the picture.
I am not going to reveal the solution at this point. See what you can discover at this point.

I think this is primarily an ESL (English as a second language) issue.

I think all five components that look like resistor ARE resistors, just that they don't all have the resistance values given in the problem statement.

 

I think this is primarily an ESL (English as a second language) issue.

I think all five components that look like resistor ARE resistors, just that they don't all have the resistance values given in the problem statement.

I can solve it with ALL the resistors and values given.
However, you have to add additional components. I arrived at one solution. I suspect that there is an infinite number of solutions but have yet to verify that.

 

I can solve it with ALL the resistors and values given.
However, you have to add additional components. I arrived at one solution. I suspect that there is an infinite number of solutions but have yet to verify that.

But if you add additional components, then you have NOT solved the problem given -- you have solved a different problem. There are pretty much guaranteed to be "infinite solutions" when you get to change the problem and claim that the result is somehow a "solution" to the original problem.

Why would you need to add additional components? Certainly you could take five resistors and a 65 V voltage source and connect them up this way and then measure the voltages and currents and replace the resistance value for any given component with either the voltage across that component or the current through it and have a unique solution. The only way this wouldn't be the case (assuming a non-degenerate case, which this is) is if one or more of the values given was incorrect.

At the risk of giving too much away, the TS should consider the following:

What is the voltage across R1 required by the given information? Hint: Think about what KVL requires and then look for a loop involving R1 for which you know the voltage drops across all of the other components in the loop.

If 5 A is flowing in R5, what is the absolute most that can be flowing in R1? Hint: Assume that R4 is extremely high resistance.

Therefore what is the maximum voltage across R1?

Is this consistent with the voltage across R1 required by the given information?

 

In that case, the value of R1 as stated as 3Ω cannot be correct.

 

In that case, the value of R1 as stated as 3Ω cannot be correct.

Why not? It could be one of the other values that isn't correct as stated. For instance, what if the 10 V given across R3 should have been 20 V?

Another good exercise for the TS (or anyone, really) would be to look at the problem six different ways. Pick each component in turn and ask what the limits are on the value associated with that component assuming all of the other values are correct.

 

Why not? It could be one of the other values that isn't correct as stated. For instance, what if the 10 V given across R3 should have been 20 V?

Another good exercise for the TS (or anyone, really) would be to look at the problem six different ways. Pick each component in turn and ask what the limits are on the value associated with that component assuming all of the other values are correct.

Yes, you are right. Hence there is no solution to the problem since either something is missing or any of the stated numbers could be incorrect.

 

Yes, you are right. Hence there is no solution to the problem since either something is missing or any of the stated numbers could be incorrect.

Oh boy I'm gonna let my professor have it. Thank you guys, I've been losing my mind trying to solve this. It means alot that you put in all this effort

 

Oh boy I'm gonna let my professor have it. Thank you guys, I've been losing my mind trying to solve this. It means alot that you put in all this effort

But before you confront your professor you should work out for yourself why we have arrived at this conclusion. As @WBahn has indicated, take one item at a time and assume that its value as stated is incorrect. Find the corrected value that provides a solution to the problem.

 

Oh boy I'm gonna let my professor have it. Thank you guys, I've been losing my mind trying to solve this. It means alot that you put in all this effort

Make sure you have all your ducks in a row before you let him have it. Solve for what you can and be ready to explain to him why it's unsolvable.