Transcript Chapter 3

Chapter 3
Introduction to Basic
Electrical Circuit Materials
Conductors
Pathways that allow electrons to flow
through an electrical circuit.
 Materials for conductors:

– Copper (great conductor and fairly cheap)
– Brass (Strong and good conductor)
– Aluminum (cheap, light & good conductor)
– Silver (awesome conductor, but expensive)
Conductance

The conductivity of a material is given in
siemens (S).
1
G =
R
Resistance
Conductor Size
Cross sectional area
 Determines how much current it can
handle without overheating.
 Circular conductors size – American
Wire Gauge System – larger the
number, the smaller the cross-sectional
area. No. 14 is larger than No. 20 wire.
 Circular Mil System (see next slide)

Circular Mils
The cross sectional area of a conductor.
 1 mil = 1/1000th of an inch (0.001”)
 Circular mils (cmil) = D2 [diameter squared]
 Useful when expressing a conductor
size other than r2. Such as rectangular.

Insulation
Materials with few free electrons – does
not conduct electrons well.
 Keeps electrons harnessed.

– Rubber
– Plastic
– Synthetics
• Neoprene, Teflon, nylon, polyethylene

Codes – Page 54
Types of conductors (pg. 54)
Resistance in a Conductor

Four factors that effect the resistance of
a conductor.
– Cross-Sectional area
– Type of material
– Length of conductor
– Temperature of material
Safety
National Electric Code
 Guidelines and regulations concerning
lengths and gauge of wire as well as
safety ratings of materials and
conductors.

Special Pathways
Breadboards
 Printed Circuit Boards (PCB)
 Chasis

Circuit Devices
Switches – Control
flow
 Actuator –
mechanical device
that controls the
opening and closing
of the switch.
 SPST – Single-pole
(one path); single
throw (one circuit)

Connectors
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Ring terminal
Insulated ring
terminal
Flange terminal
Inline splice
Termination Block
Fork terminal
Stranded connector
Wire nut
Split bolt connector
Circuit Protection Devices

Fuses
– In line
– Panel

Circuit Breakers
Lighting

Incandescent Lamp
– Current flowing through a tungsten filament
gives off heat and light.
Lighting

Halogen Lamp – Tungsten filament is
inserted through a glass tube, which is
filled with helium.
Lighting

Discharge Lamps
– Florescent lamp
Lighting

Discharge lamps
– Mercury Vapor
Lighting

Discharge lamps
– Neon lamp
– Glow lamp
– Strobe lamp
Measure of light intensity
Candela - amount of light generated by
one candle.
 Lumen – term used to measure the
amount of light generated by lighting
systems.
 1 candela = 12.57 lumens (1’ from center)

Resistor is a device
used to create
desirable voltage
drops and limit
current values in
electrical circuits.
Resistors
Resistors
Carbon composition
 Thin film
 Film
 Chip resistors
 Wire wound
 Metal oxide

Resistors
Adjustable (wire wound) resistor
 Variable

– Potentiometer
Resistors

Thermisters – changes resistance
values as temperature changes.
Resistor Color
Code
Tools