# Ohm's law sign convention

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## Main Question or Discussion Point

Here the voltage is negative so the current is negative. does it matter if I traverse the circuit through the other direction? #### Attachments

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kuruman
Homework Helper
Gold Member
The negative sign means that the current is actually in the opposite direction that you have shown in the diagram.

Chandra Prayaga
The answer does not depend on how you traverse the circuit.

kuruman
Homework Helper
Gold Member
Sure it does. Why is your sign negative?

Chandra Prayaga
I think I did not make my meaning clear. The actual direction of the current (irrespective of what you initially choose in the diagram) and the numerical value of the current do not depend on how you decide to traverse the circuit.
If we go round the circuit as shown in the diagram, keeping the direction of current also as indicated in the diagram, and use standard loop law:

-5V - I (6Ω) + 3V - I (4Ω) = 0, giving a current of - 0.2 A, as Neon32 got. As Kuruman points out, the negative sign simply means that the actual current is opposite to what was shown in the diagram. so the actual current is going counterclockwise round the circuit

On the other hand, keeping the current as it is in the diagram, we can traverse the circuit in the anticlockwise direction, and get:

+5V + I (6Ω) - 3V + I (4Ω) = 0, giving a current again of - 0.2 A, with again the same interpretation of the negative sign. This is what I mean when I said the answer does not depend on the sense of traversing the circuit.

kuruman