Science:Math Exam Resources/Courses/MATH152/April 2016/Question A 25/Solution 1

We follow the hint and apply Kirchoff's current law to the top node.

The current coming into the node from the left is is $i_{1}$ , the current entering the node from the bottom is $I$ , and the current leaving the node from the right is $i_{2}$ . We therefore have $i_{1} + I = i_{2}$ . Solving for $I$ gives $I = i_{2} - i_{1}$ .

Answer: $I = i_{2} - i_{1}$