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bmarc92
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Thread moved from the technical forums to the schoolwork forums
- Homework Statement
- If the potential from each voltage source is 10V and the resistance of each resistor is 5Ohms, what is the current exiting point A into R3?
- Relevant Equations
- Loop rule: \oint {\vec{E}} \cdot \left{\vec{dl}} = 0
Junction rule: \sum{I_{in}} = \sum{I_{out}}
Consider the problem below
I used Kirchoff's loop/junction rules to correctly arrive at answer C (1.3A). Before using Kirchoff's rules I tried to get ##V_3## by treating this as a Fermi problem using the following lines of logic, but there is a flaw somewhere, can someone identify the flaw?
(a) If ##V_1 = V_2##, we can assume no current from either power source branches at junction A and everything exits through ##R_3##.
(b) If there is no current branching, we can treat each loop independently as a series circuit.
(c) If I can treat each loop independently as a series circuit,
$$I_I = \frac{V_1=10}{(R_1=5) + (R_3=5)}$$
$$I_2 = \frac{V_2=10}{(R_2=5) + (R_3=5)}$$
(d) ##I_3 = I_1 + I_2##
(e) ##I_3 = 2##
(c) & (d) & (e) follows from (b), implying each loop cannot be treated independently. But why must this circuit be treated as parallel if there is no current branching?
I used Kirchoff's loop/junction rules to correctly arrive at answer C (1.3A). Before using Kirchoff's rules I tried to get ##V_3## by treating this as a Fermi problem using the following lines of logic, but there is a flaw somewhere, can someone identify the flaw?
(a) If ##V_1 = V_2##, we can assume no current from either power source branches at junction A and everything exits through ##R_3##.
(b) If there is no current branching, we can treat each loop independently as a series circuit.
(c) If I can treat each loop independently as a series circuit,
$$I_I = \frac{V_1=10}{(R_1=5) + (R_3=5)}$$
$$I_2 = \frac{V_2=10}{(R_2=5) + (R_3=5)}$$
(d) ##I_3 = I_1 + I_2##
(e) ##I_3 = 2##
(c) & (d) & (e) follows from (b), implying each loop cannot be treated independently. But why must this circuit be treated as parallel if there is no current branching?
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