Electric Circuits

Science, Grade 6


Table Of Contents: Electric Circuits

1. Parts of an Electric Circuit
An electric circuit is a complete path that current flows through. All electrical circuits contain an energy source, wire and a load. The energy source causes charges to move on the path. A battery, power plant and generator are sources of energy. The wires connect the parts of a circuit. The load is a machine or device that is connected to the circuit by wires. The load transforms electrical energy to other types of energy, such as light or heat. Often a switch is included to control the current in a circuit. A closed switch allows the current to flow, while an open switch turns the current off because it causes the path to be broken.
2. Circuit Diagram
You can use a diagram to show the path of an electric circuit. Symbols represent each part of the circuit: the energy source, the wire, the load or resistor, and the switch. Arrows indicate the direction of the current.
3. Series Circuit
There are different types of circuits. The current in a series circuit can only flow in one path, and it must flow through all the circuit components. In this series circuit, the current flows through each of the bulbs in a sequence. Because all the loads in the circuit share the same current, the bulbs are the same brightness. Adding more bulbs increases the resistance. This causes a decrease in the current, which results in a decrease in the brightness of all the bulbs. If any of the bulbs fail in a series circuit, the current will stop flowing, and the other bulbs will stop working.
4. Parallel Circuit
The current in a parallel circuit has at least two independent paths to flow. In this parallel circuit, the current can flow through each of the bulbs without having to first flow through any of the other bulbs. If a bulb fails, the other bulbs will continue to work because the current can still flow through the rest of the circuit. The brightness of the bulbs will not change, even if others are added to the circuit. Adding loads to a parallel circuit actually decreases the overall resistance of the current because the current has more paths it can travel through.