View Full Version : Electrical question regarding ohm's law
shulta44
May 11, 2010, 03:29 PM
My question is, I have a parllel circuit. 240V, It 8A. It has 3 resistors (2 are in series with each other) I can find out that the Rt is 30 ohms using ohms law, but can I figure the value of each resistor. I came up with 45 ohms on each, but only got it by guessing. Is there an actual formula?
Thank you
Stratmando
May 11, 2010, 03:38 PM
Resistors in parallel is the Reciprocal of the Sum of the Reciprocals.
Since 2 are in series that is 1 resistance the other is your third resistor.
I will try to write the formula. You won't be able to determine the value of the 2 in series, only the total of the 2.
shulta44
May 11, 2010, 04:48 PM
Thanks Strat
KISS
May 11, 2010, 08:41 PM
If two are in series and 1 in parallel, I can basically do it in my head.
You can look at it as two 60 ohm resistors in parallel are 30 ohms.
So, one is 60 and the two in parallel are 120's.
That's only one answer.
I really need to see the circuit. You can use Kircofff's current law and write loop equations.
But
Resistors in series is: Rt=R1+R2+... Rn
Resistors in parallel is: 1/Rt= 1/R1+1/R2+... 1/Rn
If there are two identical resistors in parallel, the formula reduces to the (resistor value)/2
shulta44
May 12, 2010, 03:55 PM
Thanks guys
shulta44
May 12, 2010, 04:27 PM
Sorry maybe this can clarify. Sorry pretty rough drawing. See attachment.:)
KISS
May 12, 2010, 06:12 PM
Looks like attachment didn't make it. See "Go advanced/manage attachments". IrfanView - Official Homepage - one of the most popular viewers worldwide (http://www.irfanview.com) can re-size images.