5

Circuits: Branching currents

A second lamp (or resistive element, motor, electric pump) is added in parallel to the circuit of the figure of Phenomenon 4. This leads to a second loop and creates two junctions in the circuit. Junctions are points where wires split or merge.

Now there are three separate branches to the circuit (four if we include the wire returning to the battery or power supply, Figure 1). Measurement of the charge currents shows that the currents split at a junction. The sum of the two currents flowing away from the junction equals the current flowing toward the junction.

Interpretation

The observation that charge currents split or merge at junctions lends still more support to the notion that electric charge is neither produced nor destroyed. Here, it simply flows in closed circuits.