Wiki: “A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element”. In other words, a resistor introduces resistance in a circuit. Resistors reduce the current in a circuit and introduce voltage division.
![](https://electronics.koncon.nl/wp-content/uploads/2020/10/resisitor.jpg)
The value of resistors is determined by colored rings. In case of 1% resistors (the value can deviate 1% only) the value is given in 5 colors. Check the table below. The first 3 colors make the number. The 4th one is the multiplier. The 5th ring indicates the tolerance.
![](https://electronics.koncon.nl/wp-content/uploads/2020/10/resistor_color-682x1024.jpg)
To simplify resistor manufacture, resistor values are arranged into standard resistor values conforming to the E series. This means you cannot go to the shop and buy any value you want – it is always part of a series. The most common series are E12, E24 or E96.
![](https://electronics.koncon.nl/wp-content/uploads/2020/10/E12-1024x266.jpg)
![](https://electronics.koncon.nl/wp-content/uploads/2020/10/E24-1024x431.jpg)
So for the E12 series you have 10k, 33k, 56M, … but NO 11k for example – because it is not part of the series. Resistors also have a maximum amount of energy they can dissipate. The normal small ones that you will find in audio-circuits are 0,125W (1/8W).
Sometimes you need resistors that can dissipate much more energy, so also the package will be different. See some examples below.
![](https://electronics.koncon.nl/wp-content/uploads/2020/10/resistor_1_2_5W-1024x285.jpg)