1. Chapter 26 Direct-Current Circuits
Study resistors in series and parallel
Consider Kirchoff’s Rules
The design and use of electronic measuring instruments
R-C circuits
The applications of circuits in household wiring

2. Resistors in Series and Parallel
Figure 26-1
Resistors in Parallel
Figure 26-1
Chapter 26

3. Series and parallel combination resistors
Consider Problem-Solving Strategy 26.1.
Follow Example 26.1 guided by Figure 26.3 below.
Follow Example 26.2.

4. Kirchoff’s Rules I—junctions
The algebraic sum of the currents into any junction is zero.

5. Kirchhoff’s Laws Kirchhoff’s Current Law Proof Figure 26-7
Charge can’t build up at the junction.
Figure 26-7
Kirchhoff’s Current Law - Example
Figure 26-8
Chapter 26

6. Kirchoff’s Rules II—loops
The algebraic sum of the potential differences in any loop, including those associated with emfs and those of resistive elements, must equal zero.

7. Kirchhoff’s Voltage Law – Two Loop Example
Figure 26-8
Loop 1
Loop 1
Loop 2
Loop 2

8. Kirchhoff’s Laws - A Single Loop Circuit
Example 26-3
a) Solve for I
b) Solve for Vab
c) Solve for power output of
the emf of each battery
Figure 26-10
Chapter 26

9. Kirchoff’s Rules III—examples and strategy
Read through Problem-Solving Strategy Figure 26.9 illustrates this strategy.
Refer to Example 26.3, illustrated by Figure

10. Kirchoff’s Rules IV—examples
Refer to Example 26.4, illustrated by Figure
Consider Example 26.5.
Refer to Example 26.6, illustrated by Figure
Review Example 26.7.

11. Chapter 26

12. R-C Circuits (Chapter 26, Sec 4)
Charging a Capacitor
0.37 I0
0.63 Qf
Time Constant
Figure 26-20
Figure 26-21
(26-14)
Chapter 26

13. R-C Circuits (Chapter 26, Sec 4)
Discharging a Capacitor
Time Constant
(26-14)
Figure 26-23
Figure 26-22
Chapter 26

14. D’Arsonval’s galvanometer
We’ll call it simply “meter” henceforth.
The meter is a coil of wire mounted next to a permanent magnet. Any current passing through the coil will induce magnetism in the coil. The interaction of the new electromagnetism and the permanent magnet will move the meter indicator mounted to the coil.

15. The Ammeter and Voltmeter
The ammeter (sometimes prefixed with milli or micro because the currents to be measured are routinely thousandths or millionths of an ampere) may be used to measure current OR voltage. A shunt resistor makes this conversion as shown below in Figure
Consider Example 26.8 to follow a current example. Consider Example 26.9 to follow a voltage example.

16. Ohmmeters and digital multimeters
An ohmmeter is designed specifically to measure resistance.
Refer to Figure and Figure below to see an ohmmeter wiring diagram and a photograph of a digital multimeter. The multimeter can measure current, voltage, or resistance over a wide range.

17. Power Distribution Systems
240-V line
black, red Neutral
Black
White
120 v
One phase of the 240-V line
We buy energy from the Power Company, not power
kW x time = watt-seconds = Joules
1 kWh = (1000W) (3600 s ) = 3.6 x 106 W-s = 3.6 x 106 J

18. Fuses, circuit breakers, and GFI
A fuse will melt and a breaker will open the circuit if maximum current is reached. See Figure
GFI stops further current flow when a sudden drop in resistance indicates that someone has offered a new path to ground. I don’t know if it will save this worker we see in Figure who didn’t use a grounded drill.

19. The wiring diagram for a typical kitchen
Consider Figure below.
Follow Example

20. Average Retail Price of Electricity cents per kilowatt-hour
Residential
Commercial1
Industrial1
Census Division
and State
Nov-07
Nov-06
New England
16.18
15.58
14.19
13.78
12.75
11.44
Connecticut
18.33
16.92
14.91
14.24
12.46
12.08
Maine
15.42
14.06
13.04
11.91
12.12
9.45
Massachusetts
15.69
15.74
14.38
14.22
14.01
12.53
New Hampshire
14.8
13.26
13.28
12.32
10.78
Rhode Island
14.62
14.34
13.2
12.81
12.18
12.28
Vermont
14.35
13.57
12.36
11.84
8.79
8.31
U.S. Total
10.69
10.18
9.6
9.24
6.22
6.04

21. Chapter 26