What's the equivalent resistance?

Lay off the coke for a while senpai.

it's a messy circuit, you can't work it out with simple serial/parallel rules, you have to use KCL and/or KVL to make simultaneous equations

dude, there's no voltage or current sources...

low energy, sad
*sniff*

It's close to 10||30 = (30/4)

>Problem gets solved correctly with first post in /wsr/ while Veeky Forums either shitposts or solves it wrong.

You guys are fucking worthless.

Rab must be smaller than 10Ω
45||30=90/5=18
18+20=38 which is close to 40
40||60=120/5=24
24+7=31 which is close to 30
10||30=30/4=7.5
close enough for no calculator

Is A source and B ground?

You could think of them that way, it wouldn't change the problem.
Not relevant, though.

current doesnt flow from ground to source. So it does make a difference

kek

just put a test voltage source you nigger faggot holy shit :)

Don't ask a board for science and math about questions regarding menial labor that belongs on . Only high level discussion is allowed here.

no?
it's easy af and you can solve it easily
bro tip: the 60 ohm resistor is in parallel with the other three resistors
you just have to redraw it and you'll see

Just trace the flow of electrons. Current will not flow into itself and take the shortest route to ground. though all paths will have current through them. Any splits form a parallel

>high level discussion
Yes, like 'what is free will'.

there is no higher level than the abstract.

You do not need a source to combine components, not even values. You can write a functional expression (like Rab=R9||(R2||R4+R1)||...) which evaluates to the resistance of the circuit. You need a source if you want voltages and currents.

You need the to know where the current starts and terminates to answer the question correctly. without themn 7 and 10 would be connected in series. But they are connected in parallel because of where the source and ground are.

correct, but what is RPN? reverse polish notation?

>reverse polish notation?
Yes, first you write down the expression 10||(7+60||(20+30||45)) and then you type it in:
45[1/x]30[1/x][+][1/x]20[+][1/x]60[1/x][+][1/x]7[+][1/x]10[1/x][+][1/x]
7.516472377090724
[1/x] key converts resistance conductance which you need for the parallel paths.
I have no idea how it would be done with a normal calculator because I never had one.

This is why this board is so cancerous... cant even solve a simple eq resistance problem yet you pretend to understand shit like global warming and physical concepts beyond your comprehension

>current starts and terminates
A current neither starts nor terminates, it always runs in a loop.
>7 and 10 would be connected in series
There is a reference (points a and b), so the rest of the circuit is in parallel to 10Ω. You would connect your ohm meter (which has a source, a battery) to a and b to measure the total resistance. OP's problem wants you to predict the result based on a theory that in this case boils down to Ohm's law.

You are sounding ignorant of how things work. But ohm meters send a current through the wire to measure resistance. You need to know where the current starts and terminates.

Me again. I had the solution routine down, but my parallel resistance formula was rusty.

>45 and 30 are in parallel...start there. Those are in series with the 20. That result is in parallel with the 60, which is in series with the 7. And all that is in parallel with the 10.

Here goes the long, drawn out, old-school solution:

45 and 30 are in parallel:

1/45 + 1/30 = 1/x or 18 ohms

In series with the 20, equals 38 ohms. In parallel with the 60 ohm:

1/38 + 1/60 = 1/x or 23.265 ohms

In series with the 7 ohm, equals 30.265 ohms. In parallel with the 10 ohm:

1/30.265 + 1/10 = 1/x or 7.516 ohms for the total circuit.

Dis nigga was correct, with way less bullshit. Buy what he's selling.

You mean without further information it is impossible to calculate the effective resistance of two resistors wired in parallel?

>In series with the 7 ohm, equals 30.265 ohms. In parallel with the 10 ohm:
I don't get this part, aren't the 7 and 10 ohm resistors in series?

No, because of where the current starts and terminates. It splits running from a through the 10 ohm to b. While the rest goes through 7 and the rest of the circuit to b.

thanks, now i get it. cool stuff, i will try that.

fyi normal (scientific) calculators usually have a ^(-1) key. check pic related, second raw top-right. then you basically proceed like you did with the rpn calculator. if you don't like the memo key, you should use a lot of brackets.

Same circuit, drawn differently. The 23Ω part represents the rest of the circuit.

Thanks anons.

Why is the 45||30 in series with 20?

I mean, why not in series with 60 instead?

because it is
replace the [math]45 \Omega[/math] and [math]30 \Omega[/math] resistors by a single [math]18 \Omega[/math] resistor

another drawing

thanks kind user