Resistance/Resistor Color Coding: How to Calculate & How to Remember

in hive-148441 •  14 days ago 

One of the first things we learnt during the initial days of first year first semester's labs was "Resistances'/Resistors' Color Coding"

Resistance Color Coding 1.jpg

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It is 99.99% true that no electronic circuit is completed without a resistor.

Resistor is an electronics component which decrease the amount of current passing through it and as a result it develops a voltage (voltage drop) in between both of its terminal. Seeing it in a broader view, resistor/s create a certain voltage between two points on an electric circuit in combination with other electronic components.

Even though, you can measure the value of a resistor with a Ohm meter or multi-meter, it is better to memorize its color coding for being more productive and if you're a student of Electronics, then it's a must.

The value of a resistor is used to represent on its body with bands of different colors.

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The resistor in the above picture is a 4-band resistor (Other type of resistors are 5-band resistors), and has a value of 4.7 KΩ (4.7 Kilo Ohm).

Let's see how it can be calculated and what are the values associated with different colors.

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Remember, in a 4-band resistor, you'll find three colors closer to each other than the fourth one. To read or calculate the value of a resistor it must be held in the hand or placed on a surface in such a position that the side of those three color bands must be on the left hand side (just like in the second image of this post).

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The value, 4.7 KΩ, of the resistor in the image is calculated with the color bands starting from the left.

  • First color-band determines the value for the first digit (4 in this example).
  • Second color-band determines the value for the second digit (7 in this example).
  • From the Third color-band we get the value of "n" in "10n" or the power of 10 which is then termed and functioned as a "multiplier" (n = 2 in this example. So, multiplier = 10 2 = 100).

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By multiplying 47 with 100, we get the value 4700Ω or 4.7KΩ.

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During our studies, we used the following mnemonic to memorize resistor color coding.

Better Be Right Or Your Great Big Virtue Goes Wrong

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This is a popular mnemonic among global electronics community and you can find it online, with one exception though, online version includes "Venture" instead of "Virtue".

Thanks to it, I still remember resistor color coding.

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Another factor which should be considered when calculating the value of a resistor is its TOLERANCE.

Tolerance of a Resistor is the measurement of the percentage of error in its value. Tolerance could be in the range from 0.1% to 20% plus/minus.

Meaning...

Accurate value of a 100Ω resistor with 20% plus tolerance is 120Ω (100 + 20), and with 20% minus tolerance, it will be 80Ω (100 - 20).

It is of utmost importance to count tolerance in the total value of the resistor because when designing/making an electronics circuit, a minor change in the value can change the overall output and can cause failure to get the intended result.

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Tolerance of a resistor has its own color coding as well.

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I don't know any phrase or mnemonic to remember the Tolerance Color Coding, do share in the comments if you are aware of any.

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