DC Chapter 7
How many leads does a potentiometer have?
3
Resistors can have how many bands of colors
3 to 5
Name two types of variable resistors.
Potentiometer and Rheostat
Resistance of the Wire (symbol)
R
What is the formula for temperature change?
R change/Old R x Coef
What is the formula for resistance change?
Resistance x Coef x Temp Change
What are one of the most common components found in electric circuits
Resistors
What limits the flow to current through a cicuit
Resistors
What are made by winding a piece of resistive wire around a ceramic core?
Wire wound resistors
How many leads does a rheostat have?
2
Cross sectional area in CM (symbol)
A
American Wire Gauge (AWG) is also known as?
Brown & Sharpe Gauge (B&S)
One of the most common types of fixed resistors is the?
Carbon Resistor
A _____________ is a unit of measurement describing the cross-sectional area of a conductor.
Circular Mil
The values of a resistor can often be determined by the?
Color Code
A rope-stranded cable consists of several __________ cables twisted together
Concentric
A conductor with a smaller diameter has less resistance than a conductor with a larger diameter.
False
A potentiometer varies the amp
False
Resistance is higher on a cold wire than a hot wire
False
What have only one ohmic value that cannot be changed or adjusted?
Fixed Resistors
Resistivity of the material (ohms per mil-foot)(symbol)
K
Length in Feet (symbol)
L
A hot lamp draws ______ current than a cold lamp
Less
A ________ is a unit for measuring the diameter of a wire, equal to one thousandth of an inch (0.0254 millimeters).
Mil
_____________ is a conductor with a 1 mil (0.001 inches) diameter and a length of one foot, used as a standard for defining resistivity of a given material.
Mil-Foot
What is the name of the special resistance wire used in heating appliances?
Nichrome
The first two color bands on a resistor represent what?
Numerical Values
Resistors are rated by __________ and __________.
Ohms and watts
List the four factors that can determine the amount of resistance, what are they?
Temperature, Material, Gauge, Length
The third color band on a resistor is called what?
The Multiplier
The fourth band on a resistor represents the what?
The Tolerance
A rheostat varies the amperage.
True
A standard wire has the same amount of copper and the same current-carrying capacity as a solid wire of the same size.
True
A _______________________ is a resistor whose values can be changed or varied over a range
Variable resistor
The second principal function of resistors is to produce a?
Voltage Divider
Not only is the resistance greater as the temperature rises, but it is also increasing at a _____________ rate as the temperature rises
faster
Carbon resistors are very popular for most applications because they are ___________ and ______________
inexpensive, readily available
Material that tend to prevent current from flowing through them
nonconductors or insulators
As a lamp turns _____, the resistance of the filament increases sharply
on
As the temperature approaches absolute 0 many metals and alloys lose all their electrical resistance. This behavior is called what?
superconductivity
