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

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

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

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

5. 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.

6. 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

7. 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

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

9. 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

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

11. 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

12. 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

13. 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 =
= A
= 20 mA

14. Calculating ResistanceB1
24 V A
0.03 A V I =
24 V
0.03 A
R =
= 800 W
= 0.8 k W

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

16. 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

17. 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

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