Resistor Shorting and Kirchhoff's Rule Explanation

[member 217843]

Homework Statement

What would the current I1 be in the figure below if the 18 Ω resistor is shorted out (resistance = 0)? Let r = 1.0 Ω.

Homework Equations

I used Kirchhoff's Rule

The Attempt at a Solution

I figured this problem out, but I had trouble, and I'm not sure I understand why the answer is what it is. I'm confused about the resistor shorting out. At first, I wrote out the problem not including the shorted out resistor, as the resistance became 0 when it shorted out. However, this was wrong. I then attempted the problem including the 18 ohm resistor, and I got the correct answer.

Can someone explain to me why you need to include the shorted out resistor?

Note: I simply want to understand why, I don't need the problem worked out, as I already found the numerical answer.

 

[cjl]

You had it right the first time. If the resistor is shorted, it should not be included in the calculations. It sounds like the solutions you were given might be incorrect.