The value of resistors can be calculated from their color bands on its surface.The first band uaually have width greater than others.
The numbers 0,1,2,3,4,5,6,7,8 and 9 represent the colors of black,brown,red, orange,yellow,green,blue,violet,grey and white respectively.
The last band indicates tolerance of a resistor. For instance, First band is brown,representing the number 1 and second band is black representing number 0 and third band is red representing 2 zeros because red has number 2.The fourth band may be gold,brown,red or silver representing tolerence.
The first three bands are needed to calculate the value of resistors. The value of resistor is 1000 Ohm which can be written as 1 kilo Ohm (kΩ).
Resistance value can be also measured by multimeter. Various types of resistors are now augmented in electronic system.Especially Variable resistors find their application in potentiometers, strain gauge and iron box.