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Help solving a circuit (resistor network)

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elektro85

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Hei

I´m struggling with a new circuit analyze. The question is to determine the equations using KCL and KVL.
And then use superposition to solve current over R7 using :
I=1A, R1=1ohm r4= 1 ohm R5=R6=5 ohm R7=10 ohm V=10V

I would be so happy if someone could help, or maybe recommend som good books or web sites to use.
 

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Hi
you need basic circuit analysis and it can be found in any circuit analysis text books
such as "Engineering Circuit Analysis by William Hart Hayt," or "Basic Circuit Theory, Charles A. Desoer, Ernest S. Kuh"

as a hint
first you must short the voltage source do KCL and find current on R7
then open the current source , convert voltage source and R1 to NORTON equivalent again do KCL and find R7 current .
add those values that you found in previous sections
 

elektro85 said:
Hei

I´m struggling with a new circuit analyze. The question is to determine the equations using KCL and KVL.
And then use superposition to solve current over R7 using :
I=1A, R1=1ohm r4= 1 ohm R5=R6=5 ohm R7=10 ohm V=10V

I would be so happy if someone could help, or maybe recommend som good books or web sites to use.
Click to expand...

Looks to me like you can solve the problem with 4 equations using the node method and 5 equations with the loop method.

Ratch
 

I tried mesh but I got 4 equations using it, i sat up one for the loop with voltage source , 2 loops for the current, and one for the loop with R7. Where do you have your last loop?
 

first thing,
we can't apply KVL if the loop is having current source.
we can't apply KCL if the loop is having voltage source.

if there is like this problems,
we can apply easily supermesh or supernode.



in supermesh,we have to consider current source is open circuit and,
in supernode, voltage source as short circuited.

and for applying superposition theorem, we will needed R2 and R3 values.
I am using 'U.A. patel' book subject :circuits and networks.
 

Why do you call the pile of resistors a circuit? A circuit has a function. What is the function of your pile of resistors? School work? I have worked in electronics for many years and I have never seen a "circuit" like that.
 

Good question, this is a simple circuit according to my professor. This is school work for a subject in basic electronics for process technology. I don´t think It´s a function here, only to make it hard for us, so that we can show that we understand, which I clearly don´t.
 

Apply Superposition Theorem and the answer will be straightforward if you would have R2 and R3.
 
Last edited:

Audioguru said:
Why do you call the pile of resistors a circuit? A circuit has a function. What is the function of your pile of resistors? School work? I have worked in electronics for many years and I have never seen a "circuit" like that.
Click to expand...

Training.jpg

Wow! Why they do that?
Why they call football players?

I played football for years and never saw it during a match.

;-)
 

elektro85 said:
I tried mesh but I got 4 equations using it, i sat up one for the loop with voltage source , 2 loops for the current, and one for the loop with R7. Where do you have your last loop?
Click to expand...

I was wrong. Only takes 3 equations for mesh or loop analysis. You already know that the west loop is -1 amp. Tell us what the values R2 and R3 are. Then show us your work. Refer to your loops as north, east, south, and west. Superposition is not necessary.

Ratch
 

elektro85 said:
Hei

I´m struggling with a new circuit analyze. The question is to determine the equations using KCL and KVL.
And then use superposition to solve current over R7 using :
I=1A, R1=1ohm r4= 1 ohm R5=R6=5 ohm R7=10 ohm V=10V

I would be so happy if someone could help, or maybe recommend som good books or web sites to use.
Click to expand...

Why the values of R2 and R3 are not given? Their values are not relevant?

Remember that a voltage source has zero resistance and a current source has infinite resistance.
 

elektro85 said:
I tried mesh but I got 4 equations using it, i sat up one for the loop with voltage source , 2 loops for the current, and one for the loop with R7. Where do you have your last loop?
Click to expand...

Only 3 equations because I isn't unknown.

Clipboard-3.JPG

The standard mesh eq are:
(R1+R2+R5) I1 - R5 I3 + R2 I = V
(R3+R4+R6) I2 - R6 I3 + R3 I = 0
(R5+R6+R7) I3 - R5 I1 - R6 I2 = 0

no need a 4th equation because I is not unknown

Then, the final system

(R1+R2+R5) I1 - R5 I3 = V - R2 I
(R3+R4+R6) I2 - R6 I3 = - R3 I
(R5+R6+R7) I3 - R5 I1 - R6 I2 = 0
 

c_mitra

What do the impedances of the voltage and current sources have to do with solving the problem?

Ratch

- - - Updated - - -

elektro85 said:
Hei

I´m struggling with a new circuit analyze. The question is to determine the equations using KCL and KVL.
And then use superposition to solve current over R7 using :
I=1A, R1=1ohm r4= 1 ohm R5=R6=5 ohm R7=10 ohm V=10V

I would be so happy if someone could help, or maybe recommend som good books or web sites to use.
Click to expand...
**broken link removed**

The expressions would simplify if the values of R2 and R3 were known.

Ratch
 
Last edited:

Simulate it and compare the results to your equations until you understand your equations.
 

Ratch said:
c_mitra

What do the impedances of the voltage and current sources have to do with solving the problem?

Ratch

- - - Updated - - -


**broken link removed**

The expressions would simplify if the values of R2 and R3 were known.

Ratch
Click to expand...

Trying to view your attachment gives an error.
 

Ratch said:
What do the impedances of the voltage and current sources have to do with solving the problem?
Click to expand...

Because you have a voltage source and a current source in series and it may appear puzzling...
 

elektro85 said:
R4= 1 and R3 = 5
Click to expand...

you should give us all informations. you are giving value of R3 now!! no matter, but you also include that R2 has any value or not. give attention. :thumbsup:
 

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