My equation for R2 is:
R2=(VL*r + VL(375))/12
I made a calculator mistake:
For VL= 4; r = 100
R2 = (4(100)+4(375))/12
R2 = 158.33
R1 = 375-R2 = 216.67
:) EEEEEEEEEEEeeeeeeeeeeeeeeeeeeeeeee!
Okay now I got these solution sets:
VL = 5; r = 5
R1 = 216.67 ohms
R2 = 158.33 ohms
VL = 4; r = 100
R1 = 60.42 ohms
R2 = 314.58 ohms
I'm still uncomfortable with there being two values for each resistor.
VL=(12*R2)/(r+R1+R2)
<algebra happens>
R2=(VL*r+VL*R1)/(12-VL)
But I can't substitute this back into VL=(12*R2)/(r+R1+R2) because then I would be plugging the equation back into itself.
Right well if
r=100 ohms when VL = 5v
R2=(500+5*R1)/7
and
r=5 ohms when VL = 4v
R2=(5+R1)/2
But I don't have an equation to use these in. We used my loop equation and ohms law to get these, don't I need another equation to plug these into?
I made a mistake in my first post but I have:
12-I(r+R1+R2)=0
VL=I*R2
Then you wrote this:
VL = (R2*12v) / (r + R1 + R2) but I don't know where that came from.
Using mathematica I can solve what you wrote for R2 in terms of R1
For VL = 4 :: R2=5(r+R1)/7
For VL = 5 :: R2=(r+R)/2
Following your suggestions I've gotten two sets of solutions by plugging in r={5ohms, 100ohms} and VL={5v,4v}
To get:
R1={-4,-99ohms}
R2={5/7,-1/2ohms}
Now the resistors don't have to be "real" but I'm concerned because the resistors have different values for each load voltage and I don't...
Forgive me but I don't seem to have equations like that.
My equation from Kirchoff's loop rule is: 12v - Ir - IR1 - IR2 = 0
This contains 3 unknowns: I, R1, and R2
Using ohm's law I can substitute; I = 12v / (r + R1 + R2)
It seems to me that the only equation I have that relates R1 to R2...
I seem to be missing something. What relationship have I not used yet? I can't substitute the voltage equation back into itself and I've already used Ohm's law to replace "I" with 12v/Rtotal.
Okay.
Is there any way to pull out another equation from the problem. If I am interpreting your suggestion correctly you want me to use r=5ohms then solve for the voltage across R2 and get 5 volts, then r=100ohms and get 4v. But even then I have one equation with two unknowns: R1 and R2, am I...
Homework Statement
You want to build a voltage divider for a product that uses as it's source a 12v battery and a non-zero internal resistance. You want to have an output voltage between 4 and 5 volts. The internal resistance varies from 5 ohms when fully charged to 100 ohms when the battery...
Homework Statement
Two point charges, -520x10-6C and -270x10-6C are 2 meters apart. At which point would a carbon nucleus experience zero net force?
(positive test charge)
Homework Equations
k=9x109
F=k((q1*q2)/r2) Coulomb's Law
E=k(q1/r2)=(F/q2)
The Attempt at a Solution
I really...
That certainly makes more sense than before! The worksheet must have a typo on the equation, I double checked and the handout and the -λt is the exponent of Ao and Euler's number is nowhere to be found.
Thanks alot.
If I substitute numbers in for a and b using my calculator I don't get a true statement.
a = 2
b = 5
ln(e^(a*b)) = a + b
ln(e^(10)) = 7
10 = 7
What am I doing wrong? :(