Final answer:
Kirchhoff's Junction rule asserts that the total current into a junction equals the total current out, allowing the calculation of unknown currents in a circuit by setting up and solving equations based on this conservation principle.
Step-by-step explanation:
To understand how you use Kirchhoff's Junction rule to calculate the current in a circuit, one must consider the principle that charge is conserved within an electrical junction—a point where three or more wires meet. According to Kirchhoff's Junction rule, also known as the first rule, the total current entering a junction must be equal to the total current leaving the junction. For example, if a current I₁ enters a junction, and it splits into two separate currents, I₂ and I₃, then according to Kirchhoff's rule, I₁ must equal I₂ plus I₃ (I₁ = I₂ + I₃). To calculate the unknown currents in a circuit, create equations at each junction using the junction rule and solve the system of equations sequentially or simultaneously to find the values of all the currents.