Everything is made of atoms, including humans. An atom looks like the sun with the planets spinning around it. The center is called the nucleus. It is made of tiny protons and neutrons. Electrons move around the nucleus.
When an atom is in balance, it has the same number of protons and electrons. It can have a different number of neutrons. Electrons stay in their shells because a special force holds them there. Protons and electrons are attracted to each other. Protons have a positive charge (+) and electrons have a negative (-) charge.
Moving electrons are called electricity. Electricity travels in closed loops, or circuits (from the word circle). It must have a complete path from the power source through the wires and back.
If a circuit is open, the electricity can’t flow. When we flip on a light switch, we close a circuit. The electricity flows through the light and back into the wire. When we flip the switch off, we open the circuit. No electricity flows to the light.
The current in a series circuit goes through every component in the circuit. Therefore, all of the components in a series connection carry the same current. There is only one path in a series circuit in which the current can flow.
In a parallel circuit current can flow through each of the bulbs without first having to flow through any others. If any of the bulbs fail the others will still work as current can still flow through the rest of the circuit.