ABSTRACT
Resistors are components that have a nearly 0° phase shift between voltage and current over a wide range of frequencies with the average value of resistance independent of the instantaneous value of voltage or current. Low-wattage fixed resistors are usually identified by color-coding on the body of the device. The major types of resistors are identified as Wire-Wound Resistor, Metal Film Resistor, Carbon Film Resistor, Carbon Composition Resistor, Control and Limiting Resistors and Adjustable Resistors. Variable resistors permit adjustment of resistance or voltage division by a control handle or with a tool. Carbon film resistors are similar in construction and characteristics to axial lead metal film resistors. Cylindrical wire-wound power resistors can be made adjustable with a metal clamp in contact with one or more turns not covered with enamel along an axial stripe. Variable attenuators are adjustable resistor networks that show a calibrated increase in attenuation for each switched step.
