Calculating equivalent resistance in the following circuit

Thread Starter

natrawrs

Joined Aug 10, 2010
1
Hi everyone,
I was given the following circuit and i have to work out the equivalent resistance in the circuit, given that each resistor has a resistance of 123456789 ohm. I havent learned much about equivalent resistance, I hope you could teach me some basics and steps on how to work it out. Thanks!
 

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JDT

Joined Feb 12, 2009
657
Start with assuming that a voltage is applied across the corners and therefore a current flows from A to B.

Note that a number of nodes in the array will have equal voltages and can be connected together without changing the operation. The circuit then becomes an array of paralleled resistors.

In fact there will be 2 paralleled resistors in series with 4 paralleled resistors in series with 6 ... (do you see where I'm going?).

Work it out assuming each resistor is 1 ohm then scale by 123456789.

Actually it's easy!
 

The Electrician

Joined Oct 9, 2007
2,970
Start with assuming that a voltage is applied across the corners and therefore a current flows from A to B.

Note that a number of nodes in the array will have equal voltages and can be connected together without changing the operation.
Be very careful with assumptions about this. Things are not what you think.

In fact there will be 2 paralleled resistors in series with 4 paralleled resistors in series with 6 ... (do you see where I'm going?).
This is not quite true.

Work it out assuming each resistor is 1 ohm then scale by 123456789.

Actually it's easy!
It's not as easy as you think.

See this thread:

http://forum.allaboutcircuits.com/showthread.php?t=13391
 

JDT

Joined Feb 12, 2009
657
Sorry, this comes of replying very quickly while I should be doing something else (working)!

But, I think I am right in saying that that points C have the same potential and can be connected together, and points D, and points E. Once you have done that resistors x and y can be replaced with a single resistor.

Then work it out with all resistors 1Ω and scale.

Yes?
 

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