Types of Resistors
Resistors are used in all electrical and electronic circuits to control the magnitude of current. Resistors are of two types:
- Carbon Resistors
- Wire wound Resistors
In a wire wound resistor, a resistance wire (of manganin, constantan or nichrome) of definite length, which depends on the required value of resistance, is wound two-fold over an insulating cylinder to make it non-inductive. In carbon resistors, carbon with a suitable binding agent is molded into a cylinder. Wire leads are attached to the cylinder for making connections to electrical circuits.
Color Coding of Resistors
Resistors are color coded to give their values.
R = AB × 10C Ω, D where A, B and C are colored stripes.
First two colors indicate the first two digits of the resistance value. Third color gives the power of ten for the multiplier of the value of the resistance. Fourth color (the last one) gives the tolerance of the resistance, which is 5% for golden color, 10% for silver color and 20% for body color.
| Color | Number |
| Black | 0 |
| Brown | 1 |
| Red | 2 |
| Orange | 3 |
| Yellow | 4 |
| Green | 5 |
| Blue | 6 |
| Violet | 7 |
| Grey | 8 |
| White | 9 |