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Example: Application of Node Rule
Suppose you have the circuit below. Nodes are labeled for simplicity of discussion. you are given a few values: $I_1=8 \text{ A}$, $I_2=3 \text{ A}$, and $I_3=4 \text{ A}$. Determine all other currents in the circuit, using the Current Node Rule. Draw the direction of the current as well.
Facts
- $I_1=8 \text{ A}$, $I_2=3 \text{ A}$, and $I_3=4 \text{ A}$.
- $I_1$, $I_2$, and $I_3$ are directed as pictured.
Lacking
- All other currents (including their directions).
Approximations & Assumptions
- The current is not changing.
- All current in the circuit arises from other currents in the circuit.
Representations
- We represent the situation with diagram given.
- We represent the Node Rule as $I_{in}=I_{out}$.
Solution
Let's start with node $A$.