SMD resistors are basic surface mount components that limit the current passing through them. "R" stands for resistance, and the unit of resistance is Ohm (Ω). 1KΩ equals to 1000Ω, 1MΩ equals to 1000000Ω.
There are two methods to indicate the resistance value on the SMD resistors' appearance.
1. In Arabic numbers: the first two numbers indicate the absolute numbers of the resistance value, and the last number means the power of 10.
For example, 103 means 10000Ω, 391 means 390Ω, 473 means 47000Ω.
2. In a combination of Arabic numbers and R: the Arabic numbers before the R stand for the whole part of the resistance value, and those after the R stand for the fractional part of the resistance value.
For example, R100 means 0.100Ω, 5R60 means 5.60Ω, 30R9 means 30.9Ω.
Classification of SMD resistors: according to the use differences, there are normal resistors, precision resistors, power resistors, high voltage resistors, high-resistance resistors, and high-frequency resistors.