Kirchoff's Rule: How do you determine what direction to draw your loop?

[jamba88]

Homework Statement

How do you choose which way to draw your loop when using Kirchoff's Rule?

Homework Equations

None

The Attempt at a Solution

I am guessing that it doesn't matter which way you draw your loop as long as you stay consistent with everything. However when doing a problem, I got a negative current as the answer. The book says the same value, but the current is positive not negative like I got.

 

[rl.bhat]

If you get negative answer for the current, the initial selection of the path of the current is not the actual path of the current. So you have to give the answer by changing the sign of current.

 

[tiny-tim]

Hi jamba88!

I am guessing that it doesn't matter which way you draw your loop as long as you stay consistent with everything. However when doing a problem, I got a negative current as the answer. The book says the same value, but the current is positive not negative like I got.

That's right, it doesn't matter.

hmm … either the book's answer is wrong, or yours is …

show us what you got. ​

 

[davieddy]

More to the point, when you label the current through a component,
you put an arrow on the wire. This simply states your sign convention.
Again it doesn't matter, although we usually try to guess the positive
direction.
(a negative current means current was flowing in the opposite direction).

Did the question specify a direction for the current?