Charge conservation

The principle of charge conservation states that the total electric charge in a closed system does not change.

An application of the principal of charge conservation is Kirchoff’s first law, which states: 

• The total current flowing into a junction is equal to the current flowing out of that junction.

Therefore, due to charge conservation, the distribution of current in a circuit is as follows:

• In a series circuit - 
• The current is the same everywhere in the circuit.

• In a parallel circuit - 
• The sum of the currents in each parallel set of branches is equal to the total current.