SERIES & PARALLEL CIRCUITS by Jessica A circuit that only has one conducting path is called a series circuit. This circuit has only one path for the electricity to follow, and if one of the light bulbs gets burnt out, nothing will work, because the electrical path gets broken. For example, if light bulb 1 burns out, the electricity cannot continue to flow to 2 or 3, because the path has been broken inside the bulb. A circuit with more than one conducting path is a parallel circuit. The electricity can pass through branches 1, 2, and 3. Even if one bulb dies, for example bulb 1, the electricity can still flow through branches 2 and 3. This type of circuit allows you to turn individual lights off and on. Grade 9 Science Topics Page