Basically all the materials have resistive properties but some materials such as copper, silver, gold and metal materials generally have a very small resistance. These materials deliver the electrical current very well, so-called konduktor.Kebalikan of conductive materials, ie materials such as rubber, glass, carbon has a greater resistance resist the flow of electrons, so-called as an insulator.
Resistors are the basic components of electronics are always used in every electronic circuit because it could serve as a regulator or to limit the amount of current flowing in a rangkaian.Dengan resistor, electric current can be distributed in accordance with kebutuhan.Sesuai name suggests resistor is resistive and is generally made of karbon.Satuan resistance of a resistor is called Ohm or represented by the symbol Ω (Omega).
In the electronic circuit, the resistor is denoted by the letter “R”. Judging from the material, there are several types of resistors in the market, among others: Carbon Resistor, Wirewound, and Metalfilm. There is also a resistor that can be changed in resistance value among others: Potentiometer, Rheostat and Trimmer (Trimpot). There was also a resistor that the resistance value changes when exposed to light his name LDR (Light Dependent Resistor) and a resistor that the resistance value will increase in size when exposed to hot temperatures named PTC (Positive Thermal Coefficient) and resistor resistance value will become smaller when exposed to temperatures hot whose name NTC (Negative Thermal Coefficient).
For the type of carbon and metalfilm resistors are commonly used color codes as a guide magnitude of the resistance value (resistivity) of this resistor.Resistor have a shape like a tube with two legs and kanan.Pada dikiri there is a circle form a ring body color code, the code is to know the great resistance without having to measure the magnitude of the ohmmeter.Kode colors are manufacturing standards issued by the EIA (Electronic Industries Association) as shown in table 1.1.