Resistors color code calculations

Resistors are electric components that resists current to some extent, some are made to resist large     amount of current while some only resist little current.  In electronics, it is very important to understand how to calculate resistor's resistance values inorder to use them in circuits or replace them if faulty. Resistors are labelled or coated with color bands which are use to calculate their resistance value, each band has a special code. Resistors can have four to six color codes, they are added together to calculate their resistance.

Four bands resistors have their 1-2 color codes, fifth bands have 1-3 color codes and sixth bands resistors also have their 1-3 bands color codes listed in the block below.

For easy remembrance, the above color code are shorted into this mnemonic. 

Big                   Black 

Boys.               Brown 

Race.               Red 

Our.                  Orange 

Young.            Yellow 

Girls.                Green 

But.                  Blue 

Violet.             Violet 

Generally.       Grey 

Wins.               White. 

4 bands resistor's.

3rd bands, 5 bands and  six bands resistor's 4th bands  are the multiplier value. Their codes are listed 

Resistors codes are also marked with tolerance values which means the ability of a resistor's resistance to change to increase or decrease in temperature.

Resistors with six bands have their sixth bands indicating their temperature co-efficient which dictates how the actual resistance value is changed depending on temperature.

Now that we have gotten colors and their codes, let's get into the business of calculating different resistor's resistance. Resisors have different number of bands types are listed below and how to calculate their resistance. 

1. Four bands resistors.

This types of resistors has four bands, it resistance value is calculated by adding the first two color codes followed by the third color which is the multiplier then the last which is the tolerance. 

Example.

let's calculate the resistor value shown in the image above. 

The first color is brown which has a code of (1) followed by black (0), the numbers are written together as 10. The third color (red) serves as the multiplier which has a code of (×100)  is multiplied by 10 = 10× 10^2=10000Ω shortened to 10kΩ.  The last color (gold) is the tolerance, ±5%. Therefore, the resistance value of the resistor is 10±5%kΩ

2. Five bands resistors.

This type of resistors has five bands. The first to three codes values are written to each other, the multiplier value of the fourth color is added followed by the tolerance value of the fourth color. 

For example, let's calculate the resistance value of the resistor above, the first color is brown whose code is (1), second color is brown (1), third color is black (0), these numbers are written together from the left to write (110). The fourth color is black, its multiplier value is added (×1) =110×1= 110 ohms. The last color (brown) is the tolerance which is ±1 Therefore the reistance of the above resistor is 110± ohms.

3. Six bands resistors.

This type of resistors has 6 bands, the first three codes are written together, the 5th band which is the multiplier is added and the last color code is the tolerance value. In the above resistor, it resistance value is calculated by adding the first three color codes side by sides, i.e orange (3), white (9) and black (0) = 392. The fourth color code, red(2) "the multiplier value(×100)" is added to 392 =392×100= 39200 ohms. The fifth band (brown ±1%) is the tolerance, the sixth band(red 50ppm/°c) is the temperature co-efficient. Therefore, the resistance above is 39200Ω ±1%, 50ppm/°c is shortened to 39.2kΩ ±1% 50ppm/°c