1. 18-1 Schematic Diagrams and Circuits

2. Electric Circuits
An electric circuit is a path through which charges can be conducted.
Any element that dissipates energy is called a load.
Without a load, a circuit contains little resistance to the movement of charges, which can cause a short circuit.

3. Schematic Diagrams
A diagram that depicts the construction of an electrical apparatus is called a schematic diagram.
Schematic diagrams use symbols to explain elements in an electrical apparatus.

4. Common Components

5. Open/Closed Circuits
Closed Circuit-closed-loop path for electrons to follow.
Open Circuit-when there is no charge flow and therefore no current.
Load – any element or group of elements that dissipates energy

6. EMF
The source of potential difference and electrical energy is the circuit’s EMF
Any device that transforms nonelectrical energy into electrical energy, like a battery, is a source of emf
If the internal resistance of the battery is neglected the emf equals the potential difference

7. Terminal voltage
Terminal voltage-the potential difference across the battery’s terminals
For convential current the terminal voltage is less than the emf
Vt = Emf – ir