Principles & Applications Electricity Principles & Applications Sixth Edition Richard J. Fowler Chapter 3 Basic Circuits, Laws, and Measurements ©2003 Glencoe/McGraw-Hill

INTRODUCTION Circuit Symbols Circuit Diagrams Parts of a Circuit Measuring Electrical Quantities Calculating Electrical Quantities

Symbols and Components Cell Device Symbol + Terminal Resistor Device Symbol Symbols and Components

This complete circuit uses the following: An energy or power source A control device A load Conductors Insulation (not shown)

Constructing and Checking a Lamp Circuit V mA 2 V  DC AC 20 200 2k 20K V- COM 1.52 Cell Select and arrange the components. Connect a wire from: 1) the cell to the switch, Connect the meter, 2) the switch to the light, and and flip the switch. 3) the light to the cell.

Circuit Quiz An electrical component has a ____ as well as a name. symbol The long bar on the cell symbol is the ____ terminal of the cell. positive A complete circuit has a ____ ____ that forces current to flow. power source A complete circuit often has a ____ ____ that turns the circuit off and on. control device A complete circuit has a ____ that controls the current flow. load A complete circuit has ____ that route the current. conductors

Measuring Voltage SPST Connect - lead to - terminal of source Select the dcV function R1 1 kW S1 SPST B1 15 V kW W mA mV V A + V A W COM - d c a c Connect + lead to + terminal of source

Measuring Current SPST Select the dc mA function S1 B1 15 V R1 1 kW mV V A + V A W COM - d c a c

Measuring Current SPST Connect the - lead so that electrons enter it Select the dc mA function S1 SPST kW W mA mV V A + V A W COM - d c a c Physically interrupt the circuit B1 15 V R1 1 kW Connect the + lead to the other point

Measuring Resistance SPST Select the kW function S1 B1 15 V R1 1 kW mA mV V A + V A W COM - d c a c

Measuring Resistance SPST Remove power (open switch) Select the kW function S1 SPST kW W mA mV V A + V A W COM - d c a c B1 15 V R1 1 kW Connect the leads

Measurement Quiz function positive negative current resistance Select the correct ____ of the meter before measuring an electrical quantity. function When measuring voltage, the meter’s positive lead is connected to the ____ terminal of the source. positive When measuring current, the meter’s ____ lead receives electrons from the circuit. negative When measuring ____, the meter is connected to the points created by interrupting the circuit. current Power is removed from the circuit before measuring ____. resistance

Calculating Current V R = 36 V 1800 W I = = 0.02 A = 20 mA SPST S1 B1 1.8 kW B1 36 V V R = 36 V 1800 W I = = 0.02 A = 20 mA

Calculating Resistance B1 24 V A 0.03 A V I = 24 V 0.03 A R = = 800 W = 0.8 k W

Calculating Voltage A V = IR = 0.15 A x 270 W = 40.5 V 0.15 A B1 R

Calculating Power A V IV = P = 0.2 A x 54 V = 10.8 W P = I2R = 0.2 A x 0.2 A x 270 W = 10.8 W P = V2/R = (54 V x 54 V) / 270 W = 10.8 W

Calculation Quiz Determine I when R = 10 W and V = 25 V. 2.5 A Determine R when I = 1.3 A and V = 26 V. 20 W Determine V when R = 15 W and I = 1.2 A. 18 V Determine P when I = 3.3 A and V = 16 V. 52.8 W Determine P when I = 4 A and R = 20 W. 320 W Determine P when V = 8 V and R = 16 W. 4 W

REVIEW Circuit Symbols Circuit Diagrams Parts of a Circuit Measuring Electrical Quantities Calculating Electrical Quantities