Finding the Resistance of a Fixed Resistor

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Introduction: What Is a Resistor?

  • A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. ~Wikipedia~
  • A device designed to introduce resistance into an electric circuit. ~Dictionary.com~

Basically, A Resistor is an Electrical Component that Reduces the Current Flow of A Circuit.

There are 3 Types of Color-Band Resistors

  1. 4 Band Color-Codes
  2. 5 Band Color-Codes
  3. 6 Band Color-Codes

In this Instructable, I am going to Explain Only about 4 Band Color-Codes. I may create another Instructable for the 5 and 6 Band Color-Coded Resistors.

Step 1: The Color-Code of the First Band of a Resistor

To Read the First Band, You have to know the Color-Code

Here are the Color Codes:

  • Brown - 1
  • Red - 2
  • Green - 3
  • Yellow - 4
  • Green - 5
  • Blue - 6
  • Violet - 7
  • Grey - 8
  • White - 9

Step 2: The Color-Code of the Second Band of a Resistor

To Read the Second Band, You also need to know the Color-Code

Here are the Color Codes:

  1. Black - 0
  2. Brown - 1
  3. Red - 2
  4. Green - 3
  5. Yellow - 4
  6. Green - 5
  7. Blue - 6
  8. Violet - 7
  9. Grey - 8
  10. White - 9

The Color Code for the Second Band is Similar to the First Band

Step 3: The Color-Code of the Third Band of a Resistor

And to Read the Third Band, You can guess what you need to know.

Which is that you still need to know the Color-Code for the Third Band

Here are the Color Codes:

  1. Black - 1 Ω
  2. Brown - 10 Ω
  3. Red - 100 Ω
  4. Green - 1000 Ω
  5. Yellow - 10,000 Ω
  6. Green - 100,000 Ω
  7. Blue - 1,000,000 Ω
  8. Violet - 10,000,000 Ω
  9. Gold - 0.1 Ω
  10. Silver - 0.01 Ω

For you new guys that don't know the meaning of the symbol 'Ω', It means Ohms.

Ohms is the SI Unit for Measuring Resistance.

This is the Multiplier Value for the Resistor

Step 4: The Color-Code of the Fourth and Last Band of a Resistor

To Read the Last Band in a Four Banded Resistor, You yet need another Color-Code.

The Following are the Color Code for the Fourth Band of the Resistor:

  1. Silver - ± 10%
  2. Gold - ± 5%
  3. Red - ± 2%
  4. Brown - ± 1%
  5. Green - ± 0.5%
  6. Blue - ± 0.25%
  7. Violet - ± 0.10%
  8. Grey - ± 0.05%

This is The Tolerance Value for the Resistor

Step 5: Calculating the Resistor Value

Now, To Calculate the Value of a Resistor you will need the Numbers from The Color Code

For Example We have a 'Brown-Grey-Brown-Gold' Colored Resistor, To calculate it we need to Find the Colors in the Color Code

  • Brown (First Band) : 1
  • Grey (Second Band) : 8
  • Brown (Third Band) : 10
  • Gold (Fourth Band) : ± 5%

First, Place the First number and Second Number Together. (1 and 8 = 18)

Second, Multiply the Number With the Multiplier (Third Band). (18 x 10 = 180 ohms)

So the Resistor Value is 180 ohms.

For the last Band, That is the Tolerance Value (which I may Explain in another Instructable), The Resistor have a Tolerance Value of ± 5%.

So it is an 180 ohms Resistor with 5% Tolerance.

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    4 Discussions

    This is the alternative, if you dont have a meter :)

    It is also Educational, I guess.

    0
    user
    pfred2

    2 years ago

    Your resistor looks like Brown, Black, Yellow to me. That would make it a 100K resistor.

    1 reply

    The picture on the First step was only an example of a resistor, not for the calculating example in the 6th step. The resistor picture is an 100 K Resistor :D

    At the 6th step, I have added a picture of what I was calculating :)