 Schematic Diagrams:

Objectives:

1.    Be able to interpret a circuit diagram?

2.    Determine the equivalent resistance of circuits having two or more resistors.

Key Terms:

Schematic diagram

Notes:

The schematic diagram is simply an electrical map.  Schematic diagrams are used by electrical engineers to describe the electron source, electron path, and components of a circuit.

Symbols: (www.mitedu.freeserve.co.uk/ Prac/images/active.gif)

1)    Battery

The battery is displayed as a long line opposite a short line the short line denotes the negative terminal when more than one set is present it indicates more than one source

2)    Resistor resistance is shown as a zigzag line wires without resistance are completely straight

3)    Switches

Switches can be closed or open, push button, rotary, or switched. Switches are indicated by two circles and a line inbetween in a closed circuit the line connects the two circuits (carcino.gen.nz/stuff/images/ Miller1sch.gif)

The above diagram is an example of simple circuit.  Can you find the eight different components of this circuit?

Combination Circuits: (www.doctronics.co.uk/ images/res17.gif)

To find the overall resistance, the first step is to calculate the resistance of the parallel elements. You already know that the combined resistance of two 1 resistors in parallel is 0.5 , so the total resistance in the circuit is 1+0.5=1.5 . The power supply current is:  (www.physics.uoguelph.ca/tutorials/ ohm/ohmE30.gif) 