In a parallel circuit voltage across each of the components is the same, and the total current is the sum of the currents flowing through each component every device must function for the circuit to be complete. If one bulb burns out in a series circuit, the entire circuit is broken.
The purpose of a switch in a series circuit is to make it easy to open or close the electrical circuit, turning the flow of electricity on or off. A light bulb in a series circuit is used to determine whether or not electricity is flowing.
