Question

Four wires meet at a junction. it is assumed that two currents, i1 and i4, enter the node. an ammeter records a value of +4a for i1. currents i2 and i3 are travelling out of the node. i2 has 3a running through it, and i3 has 0.5 a running through it. what is the current in i4?

Answer 1

Kirchhoff’s Current Law states that sum of entering currents is equal to sum of exiting currents.

`I_(IN) = I_(OUT)`

We are given information:

`I_(1) = 4A \\ I_(2) = 3A \\ I_(3) =0.5A \\ I_(4) = ?`

Kirchhoff’s Current Law for our example is:

`I_(1) + I_(4) = I_(2) + I_(3)`

`4 + x = 3 + 0.5`

`4 + x = 3.5`

`x = -0.5A`

We got negative value for current. This means that current I₄ is not entering but it is leaving from the junction.