View Full Version : Find the resistance of CD (Rcd)
pop000
Nov 18, 2011, 07:41 AM
in the picture you can what I did till I stuck.
NO.1 is the source, and NO.2 is after I found the equivalent resistance R-5,6,7 (which is in parallel).
but now I think R2 and R1 is also parallel but I am not sure.
all I know that is the final answer should be Rcd=3-ohm
thanks.
ebaines
Nov 18, 2011, 08:52 AM
in the picture you can what i did till i stuck.
Pop - you need to attach the figure.
pop000
Nov 18, 2011, 08:59 AM
Oh again is happened sorry :)
ebaines
Nov 18, 2011, 09:32 AM
The dead short can be thought of as a 0-ohm resistor in parallel with the 6 ohm. That makes the combination equivalent to 0 ohms. So now you have R2 and R1 in parallel, the combination of which is in series with R3.
I see that in figure 1 you have R2= 3 ohms, but in figure 2 you show R2 = 9 ohms. Which is it?
pop000
Nov 18, 2011, 09:46 AM
"I see that in figure 1 you have R2= 3 ohms, but in figure 2 you show R2 = 9 ohms. Which is it?"
well in both R2=9ohm and R1=3ohm.where I show R2=3 ohm?
well so if you told that I have R2 and R1 in parallel, the combination of which is in series with R3.
so I get R:2,1=9*3/9+3=2.25-ohm,now we know is in series with R3 so we get 2.25+1.5=3.75-ohm
do I correct till here ?
pop000
Nov 18, 2011, 09:52 AM
ohh yes yes now I see it, my mistake OK I solve it now.
so yes R2=3.
so I get R:2,1=3*3/3+3=1.5-ohm,now we know is in series with R3 so we get 1.5+1.5=3.00-ohm
so Rcd=3-ohm this is the final answer.
sorry for the confusion.
really thanks for your help :)
ebaines
Nov 18, 2011, 09:59 AM
well in both R2=9ohm and R1=3ohm.where i show R2=3 ohm?
You show R2 = 3 ohms in the upper (see attached snippet):
so i get R:2,1=9*3/9+3=2.25-ohm,now we know is in series with R3 so we get 2.25+1.5=3.75-ohm
do i correct till here ?
Yes. However, if R2 = 3 ohms then you fget a final answer of Rcd -= 3 ohms.
pop000
Nov 18, 2011, 11:24 AM
Yes you are correct it was my mistake :)