2. Electric Circuits Part One: Electric Circuits

3. Learning Goals  Define electricity.  Describe the components of an electric circuit.  Explain the difference between a closed circuit and an open circuit.

4. Electric current  Electric current is caused by moving electric charge.  Electric current comes from the motion of electrons. current

5. Electric current  Electric current is similar in some ways to a current of water.  Like electric current, water current can carry energy and do work.  A waterwheel turns when a current of water exerts a force on it.

6. Electric Circuits  An electric circuit is a complete path through which electric current travels.  A good example of a circuit is the one found in an electric toaster.

7. Electric Circuits  Wires in electric circuits are similar in some ways to pipes and hoses that carry water.

8. Electric Circuits  When drawing a circuit diagram, symbols are used to represent each part of the circuit.

9. Electric Circuits  Electrical symbols are quicker and easier to draw than realistic pictures of the components.

10. Resistors  A resistor is an electrical device that uses the energy carried by electric current in a specific way.  Any electrical device that uses energy can be shown with a resistor symbol.

12. Current in a circuit  Current only flows when there is a complete and unbroken path, or a closed circuit.  Flipping a switch to the “off” position creates an open circuit by making a break in the wire.