Technology 7 Mr. O’Rourke Intro to Electronics Technology 7 Mr. O’Rourke

How it Works: Electricity is a flow of sub-atomic (very, very small) particles, called electrons. Electrons move from a atom to atom when an electrical charge is applied across the material.

Water/Pipe Analogy: Wires: can be thought of as smooth pipes that allow water to pass through easily. Usually made of copper, which offers low resistance to the flow of electricity Electric current, expressed in amperes is a measure of how fast the current (or water) is flowing through the wire (pipe).

The Battery: To make water flow through a pipe, we need a pump. This is accomplished through the use of a battery or other power source.

Voltage: Expressed in volts. A measure of how strong the electric charge from your power source is. + or – indicate which direction electricity (water) will flow.

The Switch: Similar to a faucet or valve, you use a switch to turn the electricity off in your circuit. A switch connects (closed or on) or disconnects (open or off) the wires in your circuit.

Resistors: Why is the water pipe that goes to your kitchen faucet smaller than the main supply line to your house? Because you don’t need as much water at that location. Pipe size limits the water flow. Similar to electricity, except that wires have so little resistance, they would have to be super thin (brittle) to limit the flow of electricity.

Resistors (cont’d): Water flow through a large pipe could be limited by clogging the pipe with an object (rocks), which would slow the flow but not stop it. Resistors are like rocks, resistance is measured in ohms. Lower value resistor increases current

Things to Remember: Electrons are the particles that flow between atoms as part of an electrical current. A short circuit occurs when wires or components from different parts of the circuit accidentally connect. A battery produces electricity using a chemical reaction. To decrease the current in a circuit you may decrease the voltage or increase the resistance.

Cont’d: Materials which have very high resistance are called insulators, materials with very low resistance are called conductors. Adding resistors in parallel decreases resistance, while adding resistors in series increases resistance. The electrical resistance of water decreases when salt is dissolved in it.

Cont’d: Capacitors are components that can store voltage for periods of time. Capacitors have low resistance to alternating current and high resistance to direct current. Adding capacitors in parallel increases the capacitance while adding capacitors in series decreases the capacitance.