Post by: run-bandit on February 27, 2010, 09:04:18 am
Q) what is the output voltage of circuit if a load of resisoance 4.4k ohms is conected across the output terminals of the voltage divider?
and the
book answer is
A) effective = 1/4.4 + 1/4.4 = 2.2k ohms so Vout=3.0
I did not make the assumption i have proposed when I first did the question. as a result, my answer was 6V with the R effective being the full 4.4k ohms for R2 (which i think the solutions are talking about)
Post by: run-bandit on February 27, 2010, 08:05:08 pm
:(
Post by: /0 on February 27, 2010, 08:13:06 pm
If it's connected across the 4.4k resistor output terminals (as the working seems to show), then
Post by: QuantumJG on February 27, 2010, 08:14:45 pm
Post by: run-bandit on February 27, 2010, 08:55:20 pm
Post by: Blakhitman on February 27, 2010, 09:26:32 pm
Post by: run-bandit on February 28, 2010, 04:40:52 pm
I think this is the diagram in questionI GIFT YOU 1000 INTERNETS!!
thank you!!
Post by: Blakhitman on February 28, 2010, 04:45:03 pm
Post by: run-bandit on February 28, 2010, 08:42:49 pm
anyone at all
Post by: Mao on March 01, 2010, 10:53:42 pm
In this case, however, the component connected across V-Out is a simple resistor, and it has the same resistance as R2. Hence, treat it as a simple resistor circuit.
Post by: run-bandit on March 02, 2010, 06:44:53 pm
Components connected across V-Out usually has a very high effective resistance compared to R1 and R2. The voltage divider formula is only an approximation of what actually happens.
In this case, however, the component connected across V-Out is a simple resistor, and it has the same resistance as R2. Hence, treat it as a simple resistor circuit.
In most resistor circuits Vout doesn't automatically have the same resistance as R2...
Post by: Mao on March 03, 2010, 12:47:15 am
Components connected across V-Out usually has a very high effective resistance compared to R1 and R2. The voltage divider formula is only an approximation of what actually happens.
In this case, however, the component connected across V-Out is a simple resistor, and it has the same resistance as R2. Hence, treat it as a simple resistor circuit.
In most resistor circuits Vout doesn't automatically have the same resistance as R2...
They specified the resistance to be 4.4kohms
"a load of resisoance 4.4k ohms is conected across the output terminals"
Post by: Collin Li on March 03, 2010, 12:53:58 am
Definitely scored a click/eyeball from me :)
You're gonna get places, hahaha.
Post by: run-bandit on March 04, 2010, 08:12:43 pm
Components connected across V-Out usually has a very high effective resistance compared to R1 and R2. The voltage divider formula is only an approximation of what actually happens.
In this case, however, the component connected across V-Out is a simple resistor, and it has the same resistance as R2. Hence, treat it as a simple resistor circuit.
In most resistor circuits Vout doesn't automatically have the same resistance as R2...
They specified the resistance to be 4.4kohms
"a load of resisoance 4.4k ohms is conected across the output terminals"
But if you take it as just the 4.4k ohms then the solutions are wrong?
Post by: physics on March 04, 2010, 09:21:25 pm
http://library.thinkquest.org/10796/ch4/ch4.htm
its a feel good site where the questions are simple and are explained :)
Post by: Mao on March 05, 2010, 10:24:19 am
Components connected across V-Out usually has a very high effective resistance compared to R1 and R2. The voltage divider formula is only an approximation of what actually happens.
In this case, however, the component connected across V-Out is a simple resistor, and it has the same resistance as R2. Hence, treat it as a simple resistor circuit.
In most resistor circuits Vout doesn't automatically have the same resistance as R2...
They specified the resistance to be 4.4kohms
"a load of resisoance 4.4k ohms is conected across the output terminals"
But if you take it as just the 4.4k ohms then the solutions are wrong?
See attached
The solution (Vout = 3) is incorrect, it should be Vout = 4.5
Post by: run-bandit on March 05, 2010, 07:04:14 pm
Components connected across V-Out usually has a very high effective resistance compared to R1 and R2. The voltage divider formula is only an approximation of what actually happens.
In this case, however, the component connected across V-Out is a simple resistor, and it has the same resistance as R2. Hence, treat it as a simple resistor circuit.
In most resistor circuits Vout doesn't automatically have the same resistance as R2...
They specified the resistance to be 4.4kohms
"a load of resisoance 4.4k ohms is conected across the output terminals"
But if you take it as just the 4.4k ohms then the solutions are wrong?
See attached
The solution (Vout = 3) is incorrect, it should be Vout = 4.5
Hooray!