resistores

Resistors are passive two-terminal electrical components that implement electrical resistance, limiting and controlling current in circuits. They are used to set signal levels, create stable bias points for active devices, divide voltages, and terminate or damp signals. Resistance is measured in ohms, symbolized by the Greek letter omega. Ohm’s law, V = IR, describes how voltage, current, and resistance relate in a resistor.

Fixed resistors have a single nominal value, while variable resistors allow adjustment of resistance. Common adjustable types include potentiometers and trimmers, used for tuning and calibration. Resistors are manufactured in various constructions, including carbon composition, carbon film, metal film, metal oxide, and wire-wound. These differ in factors such as noise, temperature behavior, power rating, and precision. Packages vary from through-hole axial resistors to surface-mount devices (SMD); SMD resistors are common in compact, automated assemblies.

Key specifications include power rating, tolerance, and temperature coefficient. Power rating indicates the maximum heat the resistor can safely dissipate, typically from 1/8 watt to several watts. Tolerance describes how far the actual resistance may differ from the nominal value, commonly ±1%, ±2%, ±5%, or ±10%. Temperature coefficient, stated in parts per million per degree Celsius (ppm/°C), indicates how resistance changes with temperature.

Resistors are fundamental components in many applications, such as voltage dividers, bias networks for transistors, pull-up or pull-down networks, signal attenuation, and filter circuits. They are available in a wide range of values and configurations to suit diverse electronic designs.