Resistors Flashcards
The amount of resistance to current is measured in ____. The more of it a resistor has, the higher its resistance.
Ohms
Just as a resistor is abbreviated with the letter R, ohm is abbreviated with the Greek letter _____?
Just as a resistor is abbreviated with the letter R, ohm is abbreviated with the Greek letter omega (Ω).
What is inversely proportional with resistance?
Current
The resistor is represented by what schematic symbol?
The resistor is represented by either a rectangle or a zig-zag line.
Resistors are classified in what two types?
Fixed or Variable
Fixed resistors are classified in what three categories?
General purpose
power
precision
The most widely used general purpose resistor is the _____. Carbon resistors are identified by ________which indicate their value.
The most widely used general purpose resistor is the carbon resistor. Carbon resistors are identified by color bands which indicate their value.
What’s the difference between a carbon compostion and carbon film resistor?
CARBON COMPOSITION - A mixture of materials, mostly carbon, that is formed into a cylindrical shaped body. The amount of the other materials determines the resistance.
CARBON FILM - A strip of carbon that is wound around a core. The length of carbon determines the resistance.
Which resistors is used when a circuit has a large amount of current flow.
Power resistors
Which resistors are used when an exact value of resistance is necessary for correct circuit operation?
Precision
What are the two types of variable resistors?
What is the schematic symbol?
Which one is used for low or high current?
Potentiometers are used when circuit current flow is low.
Rheostats are used when circuit current flow is high.
What are the three general characteristics of resistors?
Power rating
Tolerance
Ohmic Value
The power rating of a resistor describes what?
The power rating describes the amount of heat a resistor can safely give off.
Resistance is a lot like friction; both act to oppose motion and, in doing so, generate heat.
Carbon composition resistors typically come in five sizes and power ratings. The power rating is measured in what?
Carbon composition resistors typically come in five sizes and power ratings. The power rating is measured in watts.
The power rating on a wound resistor (power resistor) is identified by the what markings?
PW or CW.
The letters used to identify the power rating can vary from one manufacturer to another.