 81
 0
1. Homework Statement
I attached a screenshot of the problem(s) that my professor gave in a practice exam.
2. Homework Equations
∑I = 0 at each junction
∑V = 0 at each closed loop
P = I^{2}R = V^{2}/R
R_{series} = R_{1} + R_{2} +...
3. The Attempt at a Solution
Part A:
I think the current I in the center, broken line of current, is zero because that wire is broken. Then
I_{1}+I_{2} = 0. So I_{1} = I_{2} = I
Going around the large loop, starting from the battery at the top:
V + V  IR  IR = 0
2V = 2IR
V=IR
12 = I(10)
I = 1.2
In the bottom loop...
V_{a} + V  IR + V = V_{b}
V_{a}  V_{b} = 2V + IR
V_{a}  V_{b} = 2(12) + (1.2)(10)
V_{a}  V_{b} = 12V in absolute value...
Is absolute value what I'm looking for? +12V is the answer in the solutions my professor provided.
Part B:
R_{series} = R_{1} + R_{2} +...
R_{series} = 10 + 10
R_{series} = 20
P = I^{2}R = V^{2}/R
P = (1.2)^{2}(20) = 28.8W
P = (12)^{2}/(20) = 7.2W
These aren't equal. I tried it with R in parallel as well (R_{eq} = 5), and it's still wrong. In the answers provided each of the power equations are multiplied by 2 and R = 10. Why is all of this?
Thanks!
1. Homework Statement
2. Homework Equations
3. The Attempt at a Solution
I attached a screenshot of the problem(s) that my professor gave in a practice exam.
2. Homework Equations
∑I = 0 at each junction
∑V = 0 at each closed loop
P = I^{2}R = V^{2}/R
R_{series} = R_{1} + R_{2} +...
3. The Attempt at a Solution
Part A:
I think the current I in the center, broken line of current, is zero because that wire is broken. Then
I_{1}+I_{2} = 0. So I_{1} = I_{2} = I
Going around the large loop, starting from the battery at the top:
V + V  IR  IR = 0
2V = 2IR
V=IR
12 = I(10)
I = 1.2
In the bottom loop...
V_{a} + V  IR + V = V_{b}
V_{a}  V_{b} = 2V + IR
V_{a}  V_{b} = 2(12) + (1.2)(10)
V_{a}  V_{b} = 12V in absolute value...
Is absolute value what I'm looking for? +12V is the answer in the solutions my professor provided.
Part B:
R_{series} = R_{1} + R_{2} +...
R_{series} = 10 + 10
R_{series} = 20
P = I^{2}R = V^{2}/R
P = (1.2)^{2}(20) = 28.8W
P = (12)^{2}/(20) = 7.2W
These aren't equal. I tried it with R in parallel as well (R_{eq} = 5), and it's still wrong. In the answers provided each of the power equations are multiplied by 2 and R = 10. Why is all of this?
Thanks!
1. Homework Statement
2. Homework Equations
3. The Attempt at a Solution
Attachments

11.8 KB Views: 239