What is the Equivalent Resistance between Points A and B?

AI Thread Summary
The discussion focuses on calculating the equivalent resistance between points A and B in a circuit. The initial attempt yielded an answer of 12.63 ohms, but further analysis revealed that the 4-ohm and 2-ohm resistors are in series, combining to 6 ohms, which then pairs with the 3-ohm resistor in parallel, resulting in 2 ohms. Clarification was provided that the 10-ohm resistor is not in series with the 2-ohm resistor due to alternative current paths, while the 1-ohm and 2-ohm resistors are indeed in series. Suggestions were made to re-draw the circuit for better clarity in understanding the connections.
tmr0116
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Homework Statement


Find the equivalent resistance between points a and b in the figure

Homework Equations


1/Req = 1/R1+1/R2... for parallel
Req= R1+R2... for series


The Attempt at a Solution


12.63 ohms
 

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tmr0116 said:

Homework Statement


Find the equivalent resistance between points a and b in the figure

Homework Equations


1/Req = 1/R1+1/R2... for parallel
Req= R1+R2... for series


The Attempt at a Solution


12.63 ohms

If you show your work, we can spot your errors and guide you. Or are you just asking if your answer is right?
 
I have that the 4 and 2 ohm resistor are in series and add to be 6 ohms equivalent resistor. The 6 ohm resistor and the 3 ohm resistor are parallel and 1/6+1/3=1/2 or 2 ohms equivalent. I don't know what to do next though. Are the 1, 2, and 10 ohm resistors in series?
 
tmr0116 said:
Are the 1, 2, and 10 ohm resistors in series?
No. If two elements are in series, all the current that goes through one has to go through the other. A current flowing through the 10-ohm resistor can go through the 9-ohm resistor or the 2-ohm resistor, so the 10-ohm resistor and the 2-ohm resistor are not in series. In contrast, all of the current in the 2-ohm resistor must also go through the 1-ohm resistor, so those resistors are in series.
 
Try re-drawing the circuit with your new values ... it may become clearer that way. Sometimes, it helps to re-draw the circuit vertically: in your case with "a" at the top of the diagram and "b" at the bottom.
 

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