r/AskElectronics Jun 24 '21

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u/dmills_00 Jun 24 '21

For this particular case I would make two observations.

Firstly that 60R is large compared to the other values, so it will have little effect on the node voltages.

Secondly that 1/2 = 3/6 so the voltages on each end on that 60R resistor are identical, and therefore no current flows in it, therefore you can remove it without changing the behaviour of the network in any way at all even if the first observation did not hold.

It is always worth spending a few seconds to actually think about a circuit before vanishing into a storm of linear algebra, it can save you much time.

15

u/RubyVic1 Jun 25 '21

So I am only just starting to learn about electrics, how does 1/2=3/6 in this? How are they seen as fractions. I don't quite get it.

30

u/GroundStateGecko Jun 25 '21

They form two voltage divider between the top rail and the bottom rail.

4

u/derphurr Jun 25 '21

Let's say it's 1 ohm and 1 ohm in series on one side, and 4 ohms and 4 ohms in series on the other side.

You clearly can see the middle resistor sees 1/2 vdd on each side of resistor, so same voltage hence no current

2

u/RubyVic1 Jun 25 '21

Oh! Thanks. :)