2. Saudi Aramco: Company General Use
Overview
Conclusion / Review
Examples
Resistor Tolerance
Resistor Color Codes
Review: What is a Resistor?
3. Saudi Aramco: Company General Use
Review: What is a Resistor?
Resistors – circuit component that resist (limits)
the flow of electrons in an electrical circuit.
4. Saudi Aramco: Company General Use
Resistor Color Codes
• Resistors have their resistance value and tolerance shown by
colored bands.
• Read the resistor bands from the left-hand side.
• 1st band is the one closest to one of the ends.
• 4th band will have either gold, silver, or no color.
5. Saudi Aramco: Company General Use
Resistor Color Codes
• 1st band = 1st significant digit
• 2nd band = 2nd significant digit
• 3rd band = multiplier
• 4th band = tolerance
6. Saudi Aramco: Company General Use
Resistor Color Codes
Bright
Boys
Rise
Over
Your
Grades
By
Very
Good
Work
7. Saudi Aramco: Company General Use
Resistor Color Codes
Question: Why do we use color
coding in a resistor?
Ans.: For easier identification.
8. Saudi Aramco: Company General Use
Resistor Color Codes
1st band: orange 3
2nd band: white 9
3rd band: yellow 10,000
4th band: silver +/- 10%
Therefore:
39 x 10,000 = 39,000
39 kilo ohms +/- 10%
1st band: red 2
2nd band: green 5
3rd band: black 1
4th band: silver +/- 10%
Therefore:
25 x 1 = 39,000
25 ohms +/- 10%
10. Saudi Aramco: Company General Use
Tolerance
From the resistor value:
39 kΩ +/- 10%
The tolerance limits the
resistance to:
Minimum value:
39 kΩ - 10% = 35.1 kΩ
Maximum value:
39 kΩ + 10% = 42.9 kΩ
From the resistor value:
25 Ω +/- 10%
The tolerance limits the
resistance to:
Minimum value:
25 Ω - 10% = 22.5 Ω
Maximum value:
25 Ω + 10% = 27.5 Ω
11. Saudi Aramco: Company General Use
Tolerance
Question: Why does a resistor
have tolerance?
Ans.:
There is no perfect resistor with
an exact value.
Resistors are manufactured in
approximate values.
12. Saudi Aramco: Company General Use
Review & Conclusion
Review
• Calculate the resistance of the sample
resistors.
Conclusion
• You can calculate the resistance in a
resistor just by using the color bands.
