Parallel Circuits

In a parallel circuit, there is more than one way for charge to flow. The components are in different loops, which we call branches.

Below is an example of a parallel circuit:

In this parallel circuit, there is another lamp, which is not in the same loop. We add a second loop of wire, so the second lamp is in its own loop of wire. The circuit has parallel lines and components parallel to each other, which is why we call it a parallel circuit.

Circuit Rules

In a parallel circuit, electrons do not pass through all components when flowing around the circuit. This means, that when a component in a branch breaks, the components in other branches keep working.

Current in a Parallel Circuit

In a parallel circuit, the current is shared between the different branches. We measure the current using an ammeter, which is placed in series with the components.

  • Current is measured in amperes (A)

We can say that:

Itotal = I1 + I2 +I3

In other words, the total current in a parallel circuit equals the sum of the currents of each separate branch.

As the current is shared between different branches, the current in each branch adds up to the total current. For example, if the total current is 6 amperes, all the branches must add up to 6 amperes. Each branch is 2 amperes and there are three branches, which adds up to 6 amperes (2 + 2 + 2 = 6).

Keep in mind, that the ammeter should be placed next to the component you are measuring.

As we are using the same component, the lamp, we should expect the same current to flow through each branch. In this case, we have 2 amps for all three branches.

Potential difference in a parallel circuit

In a parallel circuit, the potential difference across each branch is the same as the potential difference across the cell or the battery.

  • Potential difference is measured in volts (V)

We can say that:

Vtotal = V1 = V2 = V3

In other words, the potential difference across each branch is equal.


If the potential difference going across the cell is 4 volts, then the potential difference going across each lamp will also be 4 volts. This applies to any other components in a circuit, not just lamps.

Resistance in a parallel circuit

If resistors are connected in parallel, they have a lower combined resistance. This is because the current can take multiple paths.