There are two types of electrical circuits; A collection of wires and electric components connected together in such a way that electric current can flow through them. – Series Circuit and Parallel Circuit. In Series Circuit; the components are connected end-to-end, one after the other. They make a simple loop for the current to flow round. If one bulb ‘blows’ it breaks the whole circuit and all the bulbs go out. In Parallel Circuit; the components are connected side by side. The current has a choice of routes. If one bulb ‘blows’ there is still be a complete circuit to the other bulb so it stays alight.