# Raspberry Pi_Eng_25.5.4 Resistor

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### 25.5.4Resistor

#### 25.5.4.1Meaning of Resistor

A resistor is an electronic component that has the effect of dropping voltage by interrupting the flow of current so that the current does not flow well in the electric circuit. It is often used in most electronic circuits. The unit of resistance is ohm (ohm), which is denoted by Ω.

There are various kinds of resistor depending on the characteristics. A fixed resistor is the most commonly used resistor and have a constant resistance value that does not fluctuate. A variable resistor is a resistor that allows a variable resistance value within a certain range. It is used for volume control part or other control part, and there are a rotation type and a slide type. In addition, some of them are lead type or some chip types depending on the shape of the resistor. Figure 25‑14 Resistor

Generally, when constructing a test electronic circuit, a lead type fixed resistor is often used. In electronic circuits, resistors of various resistance values are required. Therefore, it is preferable to prepare multiple resistors of resistance value that is widely used. It is also a good idea to buy a kit that are being sold with a bundle of several types of resistors together

The following shows a simple example of using a resistor when configuring a circuit. If you want to know the resistance value of a resistor, you should measure it with a multimeter or calculate it with a colored band. Here, we describe how to calculate the resistance value with the color band on the resistor surface.

Below is a resistor of typical four-color band pattern. In the four-color band, the first two bands represent the resistance value. The third color band is the multiplier, which indicates by how many powers of 10 the previous two-digit resistance value is to be multiplied. The last 4th color band represents the error tolerance or precision of the resistance value. There is also a resistance marked with five color bands. In this case, the resistance is the first three digits, the fourth is the multiplier, and the fifth is the tolerance. Color Figure Multiplier Tolerance Heat Coefficient Black 0 1 Brown 1 ×101 ±1% F 100 S Red 2 ×102 ±2% G 50 R Orange 3 ×103 15 P Yellow 4 ×104 (±5%) 25 Q Green 5 ×105 ±0.5% D 20 Z Blue 6 ×106 ±0.25% C 10 Z Violet 7 ×107 ±0.1% B 5 M Gray 8 ×108 ±0.05% (±10%) A 1 K White 9 ×109 Gold ×10-1 ±5% Silver ×10-2 ±10% K None ±20% M