How Do You Calculate Total Resistance?

Fatima Hasan
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Homework Statement



viber-image.jpg


Homework Equations


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R_b%3D%5Cfrac%7BR_a*R_b%7D%7BR_a+R_b%7D.gif


The Attempt at a Solution



2.jpg

%20%5Cfrac%7B200%7D%7B9%7D%20+%206%20%3D%206.gif
[/B]
Could anyone check my answer please ?
 

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What is RT? What is the total resistance?

Usually an answer is easier to check than to get - calculate voltages and currents and see if they work out.
 
Why are you taking ##R_1## and ##R_2## to be in parallel? Here's what your circuit looks like after your ∇ to Y transformation:

upload_2018-10-26_9-55-37.png
 

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Just to be clear, your 6.22 Ohm answer is clearly wrong for the reason outlines by gneill.
 
gneill said:
Why are you taking ##R_1## and ##R_2## to be in parallel? Here's what your circuit looks like after your ∇ to Y transformation:

View attachment 232843
26%7D%5C%5C%5C%5C%3D6+%5Cfrac%7B15%7D%7B26%7D+%5Cfrac%7B609%7D%7B26%7D%3D30%20%5COmega.gif
 

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    26%7D%5C%5C%5C%5C%3D6+%5Cfrac%7B15%7D%7B26%7D+%5Cfrac%7B609%7D%7B26%7D%3D30%20%5COmega.gif
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Much better!
 
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