In simple words “Resistor is used to reduce current”.

A resistor works by converting electrical energy into heat, which is dissipated into the air. A device having resistance to the passage of an electric current.

The two types of components are through hole resistor and surface mount components. In through hole component resistance is calculated by color code of the resistor.

COLOR	DIGIT	MULTIPLIER
Black	0	1
Brown	1	10
Red	2	100
Orange	3	1000
Yellow	4	10000
Green	5	100000
Blue	6	1000000
Violet	7	10000000
Gray	8
White	9
Gold		+(-(5%))
Silver		+(-(10%))
None		+(-(20%))

For example let us take 4 band resistor shown above.

band 1 – Green.

band 2 – Blue.

band 3 – Brown.

band 4 – Gold

First 2 color bands are considered as numbers, next color band is considered as multiple of 10’s as in table mentioned above. So, Green is 5, Blue is 6, brown is 1 x 10. Therefore we have a 560 ohm resistor.

Let us take a look at surface mount device resistor, They are very small in size and can be soldered in surface of the board. All the tiny design of printed circuit board uses surface mount device because of there size and weight.

Since these resistor are small and sensitive to heat while soldering, It should be soldered with care.

For example, Let’s calculate the resistance of the above mentioned device, 1’s position number is 10^n. other numbers are retained.

So, 10 x 10^3 =10,000 ohms or 10 Kilo ohms.