How to Identify Resistors (With Pictures)

Resistors are very common components in all types of electronic circuits. Its function is to resist the flow of current in the circuit, and that resistance is measured in ohms. Most are printed with a color code or an alphabetic code to indicate their value in ohms and their tolerance (how much their resistance can vary). You can easily identify the resistors if you learn the codes, using a very useful mnemonic device.

Steps

Method 1 of 2: Color-Coded Resistors (Axial Resistors)

Step 1. Axial resistors are cylindrical in shape with leads at each end

Step 2. Look at the resistor so that the group of 3 or 4 colored bands is on the left side

Step 3. Read the color bands from left to right

The colors in the first 2 or 3 bands correspond to the numbers 0 to 9, representing the significant digits of the resistor's ohm value. The last band indicates the multiplier. For example, a brown, green, and green banded resistor has 15 mega ohms (15,000,000 ohms). The code is like this:

Black: significant digit 0, multiplier 0
Brown: significant digit 1, multiplier 10
Red: significant digit 2, multiplier 100
Orange: significant digit 3, multiplier 1,000 (kilo)
Yellow: significant digit 4, multiplier 10,000 (10 kilo)
Green: significant digit 5, multiplier 100,000 (mega)
Blue: significant digit 6, multiplier 1,000,000 (10 mega)
Violet: significant digit 7
Gray: significant digit 8
White: significant digit 9
Gold: 1/10 multiplier
Silver: 1/100 multiplier

Step 4. Read the color in the last color band, which is on the far right

Represents the tolerance of the resistor. If there is no color band, the tolerance is 20%. Most resistors are bandless, or have a silver or gold band, but you can find resistors with other colors. The tolerance color code looks like this:

Step 5. Brown:

1 percent tolerance

Step 6. Red:

2 percent tolerance

Step 7. Orange:

3 percent tolerance

Step 8. Green:

0.5 percent tolerance

Step 9. Blue:

0.25 percent tolerance

Step 10. Violet:

0.1 percent tolerance

Step 11. Gray:

0.05 percent tolerance

Step 12. Gold:

5 percent tolerance

Step 13. Silver:

10 percent tolerance

Step 14. Memorize a mnemonic system for resistors

There are many, choose one that you cannot forget. Remember that the first color is black, and after that, each letter corresponds to a color in order from 0 to 9. One of the methods to memorize is this:

NeMaRo AnAmaVeAz VoGriBla

Method 2 of 2: Alphanumeric Coded Resistors (Surface Resistors)

Step 1. Surface resistors are rectangular in shape with terminals on opposite sides or on the same side, and are folded forward to mount on printed circuits

Some resistors have contact plates on the bottom.

Step 2. Read the 3 or 4 numbers from the resistor

The first 2 or 3 represent the significant digits, and the last indicates the number of zeros that follow. For example, a resistor that reads 1252 will indicate a resistance of 12,500 ohms, or 1.25 kilo-ohms.

Step 3. Compare the letter at the end of the code with what your tolerance represents

Step 4. A: