Circuits and Electronics

Circuits A circuit is a closed path through which a continuous charge can flow. A circuit is a closed path through which a continuous charge can flow. The path is provided by a low- resistance material, or conductor, usually wire. The path is provided by a low- resistance material, or conductor, usually wire. Circuits are designed to do specific jobs Circuits are designed to do specific jobs

The Parts of a Circuit 1. Voltage source – provides the electric potential for charge to flow through the circuit. 1. Voltage source – provides the electric potential for charge to flow through the circuit. 2. Conductor – forms a connection from the voltage source to the electronic device. Provides a closed circuit. 2. Conductor – forms a connection from the voltage source to the electronic device. Provides a closed circuit. 3. Switch – part of a circuit designed to break the closed path of charge. 3. Switch – part of a circuit designed to break the closed path of charge. 4. Electrical device – any part of the circuit that changes electrical energy into another form of energy. (called a resistor) 4. Electrical device – any part of the circuit that changes electrical energy into another form of energy. (called a resistor)

Open and Closed Circuits If a circuit is open the charges cannot complete their path and the flow is interrupted. If a circuit is open the charges cannot complete their path and the flow is interrupted. If a circuit is closed, the charges are able to flow along the path and complete movement. If a circuit is closed, the charges are able to flow along the path and complete movement. NOTE: When you turn a light switch to the “ON” position, the path is closed and the lights come on. When it is switched to the “OFF” position it opens up the path and the charge cannot flow; therefore the lights go out. NOTE: When you turn a light switch to the “ON” position, the path is closed and the lights come on. When it is switched to the “OFF” position it opens up the path and the charge cannot flow; therefore the lights go out.

Current follows the path of least resistance Short circuit – an unintended path connecting one part of a circuit with another Short circuit – an unintended path connecting one part of a circuit with another Follows a closed path, BUT not the path that was intended. Follows a closed path, BUT not the path that was intended.

Lamp connected to outlet… Functioning circuit Functioning circuit The charge flows through one wire through light bulb and then back through the second wire to the outlet. The charge flows through one wire through light bulb and then back through the second wire to the outlet. Short circuit Short circuit The cord has been damaged and the two wires inside have formed a connection. Now the path of least resistance is through one wire and back through the second wire. This leads to too much current in wire which can lead to shock in humans or can create a fire. The cord has been damaged and the two wires inside have formed a connection. Now the path of least resistance is through one wire and back through the second wire. This leads to too much current in wire which can lead to shock in humans or can create a fire.

Danger! Danger! Too much current in a circuit is dangerous. Safety devices are built into outlets that will open up the path at the outlet preventing the flow of charges. Too much current in a circuit is dangerous. Safety devices are built into outlets that will open up the path at the outlet preventing the flow of charges. This is to prevent danger to humans and to prevent fires from being started. This is to prevent danger to humans and to prevent fires from being started.