Engineering Use Circuit reduction, voltage and current divider to find i

[Neon32]

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown >[/color]

in the solution sheet, He took the 18 ohms parallel with the 9 ohms and not the 6 ohms. I don't understand why he took this approach. I was going to take 18 ohms parallel with the 6 ohms and find their equivalent resistance then I'll take the result in series with the 9 ohms and find the total resistance of the whole circuit.

https://imgur.com/a/b9UPe

 

[davenn]

in the solution sheet, He took the 18 ohms parallel with the 9 ohms and not the 6 ohms. I don't understand why he took this approach. I was going to take 18 ohms parallel with the 6 ohms and find their equivalent resistance then I'll take the result in series with the 9 ohms and find the total resistance of the whole circuit.

This looks like homework
more background on the problem would be helpful ... diagrams etc

 

[Neon32]

This looks like homework
more background on the problem would be helpful ... diagrams etc

Yes I'm uploading it. give me one minute

 

[davenn]

Yes I'm uploading it. give me one minute

OK and you should be posting in the homework section and use the correct template

 

[Neon32]

OK and you should be posting in the homework section and use the correct template

it isn't a homework though.

 

[davenn]

it's much preferable to post images in the thread
so they can be referred to easily

 

[davenn]

He took the 18 ohms parallel with the 9 ohms and not the 6 ohms.

I don't see those on the diagram

 

[Neon32]

I don't see those on the diagram

if you take a close look, you would see he took 18 parallel with 9 ohms and found their equivalent resistance.

 

[davenn]

if you take a close look, you would see he took 18 parallel with 9 ohms and found their equivalent resistance.

I assume you are referring to the 3rd diagram ?

also' you are misreading

18k = 18,000 Ohms not 18 Ohms
and
9k = 9,000 Ohms not 9 Ohms

OK now that we have that sorted out

and found their equivalent resistance.

yes that's correct and the resulting value will be in series with the 6k Ohms resistor

in the solution sheet, He took the 18 ohms parallel with the 9 ohms and not the 6 ohms. I don't understand why he took this approach. I was going to take 18 ohms parallel with the 6 ohms and find their equivalent resistance then I'll take the result in series with the 9 ohms and find the total resistance of the whole circuit.

but the 18k isn't in parallel with the 6k so your reasoning is incorrect
can you see why it isn't ?Dave

 

[Neon32]

I assume you are referring to the 3rd diagram ?

also' you are misreading

18k = 18,000 Ohms not 18 Ohms
and
9k = 9,000 Ohms not 9 Ohms

OK now that we have that sorted out
yes that's correct and the resulting value will be in series with the 6k Ohms resistor
but the 18k isn't in parallel with the 6k so your reasoning is incorrect
can you see why it isn't ?Dave

no i don't know why it isn't.

 

[cnh1995]

no i don't know why it isn't.

Are the voltages across 18k, 9k and 6k equal?

 

[davenn]

no i don't know why it isn't.

do you know the difference between series and parallel ?

which do you think it is and why ?