A series circuit is denoted by a single loop, that is, the only way to get back to any given starting point in the circuit is by passing through every component in the circuit. By their very nature, p...A series circuit is denoted by a single loop, that is, the only way to get back to any given starting point in the circuit is by passing through every component in the circuit. By their very nature, parallel circuits will produce a splitting of current, but the voltage across each component will be the same. The sum of the currents in the various branches must equal the supplied current.