1. 10.2: Electricity and Electric Circuits

2. Static vs. Current Electricity Static Electricity: charges build up in one location Current Electricity: electrons on the move

3. Current Electricity to operate electrical devices, you need a steady flow of electrons. Current electricity is the continuous flow of electrons in a circuit. The electrons flow continuously if the following conditions are met: 1.there is a continual supply of energy 2.the electrons have a a complete path to flow through (electric circuit)

4. Electric Circuits An electric circuit must include: 1.An energy source – “energizes” the electrons, ex. battery, photoelectric cell in calculator 2.a conducting wire (connector) – provides a path for current to flow 3.A load which is a device that converts electrical energy to another form of energy, ex. light bulb  Many electric circuits also include a switch that turns the circuit on or off by closing or opening the circuit.

5. Examples of Loads Converts electricity to… light bulblight energy fanmechanical energy doorbellsound energy

6. Schematic Circuit Diagrams engineers and designers of electrical circuits use special symbols that show the components and connections in a circuit. a drawing made with these symbols is called a circuit diagram.

7. Schematic Circuit Diagrams Follow these rules when you draw circuit diagrams. 1. Always use a ruler to draw straight lines for the conducting wires. 2. Make right-angle corners so that your finished diagram is a rectangle.

8. Circuit Symbols Conductor or wire –allows current to flow very easily from one part of a circuit to another.

9. Circuit Symbols Cell - supplies electrical energy -the positive end is bigger than the negative end.

10. Circuit Symbols 2 Cells Note: every time a cell is added you need to draw another cell; a battery is a combination of two or more cells

11. Circuit Symbols Ground –a connection to earth

12. Circuit Symbols Switch - an on-off switch allows current to flow only when it is in the closed (on) position

13. Circuit Symbols Lamp –a load which converts electrical energy to light

14. Circuit Symbols Resistor –A resistor restricts the flow of current

15. Circuit Symbols Ammeter –device that measures current A

16. Circuit Symbols Voltmeter device that measures voltage V

17. Circuit Symbols Motor -electrical load that converts electrical energy into movement M

18. Circuit Building Draw the circuit diagrams for each circuit described on the handout –Now try building the circuit (substitute the buzzers for the motors)