Why Is the Current Negative in This Circuit Division Equation?

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Homework Help Overview

The discussion revolves around understanding the sign of current in a circuit division equation, specifically questioning why the current is negative in a given context. The subject area includes circuit analysis and the application of Kirchhoff's Laws.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the reasoning behind the negative sign in the current equation and discuss the direction of current flow. There are inquiries about general rules for determining current direction in more complex circuits.

Discussion Status

The discussion is active, with participants providing insights into current flow direction and referencing Kirchhoff's Laws. There is an exploration of the implications of these laws on current behavior in circuits, but no consensus has been reached regarding the specific question posed.

Contextual Notes

Participants express uncertainty about the clarity of current direction in various circuit configurations, indicating a need for further exploration of general principles in circuit analysis.

Miike012
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Can someone tell me why the current I is negative and not positive?

Im guessing the equation should be:
I = (-2)(6||3)/(6). But why the negative sign?
 

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Well, the current has to flow in the opposite direction as indicated.

ehild
 
ehild said:
Well, the current has to flow in the opposite direction as indicated.

ehild

Are there any general rules to follow because I'm sure most circuits won't be as obvious
 
There are Kirchhoff's Laws.

The 2mA current of the current source flows out of the top junction, so the same current has to flow in through the resistors. The sum of the currents flowing in is equal to the sum of the outflowing currents according to Kirchhoff's Current Law. So the current flows upward through the 2 kΩ resistor.

ehild
 

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