Node voltage current direction?

In summary, when conducting node voltage analysis using KCL, it is important to remember that the sum of all currents going into a node must equal zero. This means that some currents may be going into the node while others are going out. It is acceptable to assign arbitrary current directions, but it is recommended to make realistic guesses as they may affect the final answer. If a current direction is incorrect, it will result in a negative sign when solving the equations.
  • #1
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When doing node voltage analysis with KCL. (eg sum of currents into each node = 0). Do we assume all the currents are going INTO the node, or out of the node.

maybe it's just my math but, assuming different things gives different answers. The textbook (hambley's) says that it's fine to select arbitary current directions. Should choosing arbitary currents vastly change the answer?
 
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  • #2
Currents going into the node have to come out of it. There is nowhere else for them to go.

So, some currents will be going in and some will be coming out and the total current going in must equal the total current coming out.

It is usual to assign realistic guesses of current directions to the currents and if one of them proves to be wrong, it will have a negative sign attached to it when you solve the equations.
 

Related to Node voltage current direction?

1. What is a node in a circuit?

A node in a circuit is a point where two or more components are connected. It is represented by a dot in circuit diagrams and is used to analyze the flow of current in a circuit.

2. How do you determine the voltage of a node?

The voltage of a node can be determined by using Kirchhoff's Voltage Law (KVL), which states that the sum of voltages around a closed loop in a circuit must equal zero. This can be used to create equations and solve for the voltage at a specific node.

3. What is the direction of current flow in a node?

The direction of current flow in a node is determined by the components connected to it. Current will flow from higher potential to lower potential, so the direction of current in a node can be determined by the voltage of the components connected to it.

4. How do you calculate the current at a node?

The current at a node can be calculated by using Kirchhoff's Current Law (KCL), which states that the sum of currents entering a node must equal the sum of currents leaving the node. This can be used to create equations and solve for the current at a specific node.

5. Can the direction of current in a node change?

Yes, the direction of current in a node can change depending on the components connected to it. In some circuits, the direction of current may change periodically, such as in AC circuits. However, in a DC circuit, the direction of current will stay constant unless the components are changed.

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