100 ohm carbon resistors are very useful in practical electronic and electrical circuits. These resistors are available with 3, 4 and 5 bands. Before using carbon resistors in a circuit you must read their values by solving color codes painted on those. You can do the same by using a multiimeter as well. In this tutorial post, we’re going to explain how to read the color code of 100 ohm resistor to calculate its resistance without using a multimeter. To understand the color code of a resistor, you need to know the codes associated with each colored bands. Here is the resistor color code chart.
100 ohm resistor color code with 3 bands
In a 100 ohm carbon resistor given in above image, the first two bands have the colors of brown and black respectively which contain digit codes as 1 and 0 respectively and the third band is brown which suggests the multiplier is 10. Thus, the color code of a 3 band 100 ohm resistor will be 101M and the colors of the bands should be Brown, Black and Brown. Here, M refers to no fourth band i.e. 20% tolerance. To know the codes of individual colors, please go through the Carbon resistor color code chart.
| Band number | Color | Code |
| 1st band | Brown | 1 |
| 2nd band | Black | 0 |
| 3rd band | Brown | 1 |
| No tolerance band | – | M |
Thus, the color code, 101M = \small \color{Red}100 \Omega \pm 20%.
4 Bands 100 ohm resistor color code
If this resistor has a fourth band that indicates the tolerance of the resistance value is 10%. The color code of the tolerance band is Silver which has an alphabetical code K. Then the color coding for 100 ohm resistor with 4 bands will be 101K and the colors of the bands will be Brown, Black, Brown and Silver.
| Band number | Color | Code |
| 1st band | Brown | 1 |
| 2nd band | Black | 0 |
| 3rd band | Brown | 1 |
| 4th Band | Silver (if tolerance is 10%) | K |
Thus, the color code 101K = \small \color{Red}100 \Omega \pm 10%.
Resistor Color coding of 100 Ohm resistor with 5 bands
For a five bands 100 ohm resistor, the first three digits are 1, 0 and 0 and the multiplier is 1 i.e. 100 which is coded as “0”. So, the code of a 5 bands 100 ohm resistor with 10% tolerance will be 1000K. The color code of the bands is Brown, Black, Black, Black and Silver.
| Band number | Color | Code |
| 1st band | Brown | 1 |
| 2nd band | Black | 0 |
| 3rd band | Black | 0 |
| 4th Band | Black | 0 |
| 5th Band | Silver (if tolerance is 10%) | K |
Thus, the color code, 1000K = \small \color{Red}100 \Omega \pm 10%.
This is all from this article. Hope you understand how to read color code of 100 ohm resistor to calculate its resistance value. If you still have any confusion on this topic you can ask me in the comment section.
Thank you!
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