Construction:

1. Substrate: A substrate can be an insulating material such as ceramic or fiberglass. Its primary function is to serve as a substrate with some structural support in terms of electronics and to give insulation. The substrate usually appears as cylindrical because that permits the carbon film to be wound or layered.

2. Deposition of Carbon Film: This involves covering a very thin layer of carbon over the substrate. The process can be varied in numerous methods, but the film is mostly applied in a spiral form. It is accomplished through rotating the substrate while carbon is being deposited, such that the distribution is spread evenly and the maximum surface area is covered.

3.Lead wire attachment:

On each side of the carbon film resistor, metal leads are connected. These connect to the electrical circuit in a way that enables and maintain its continuation.Leads are usually soldered with the intention of maintaining good electrical contact with mechanical stability.

4.Protective Coating:

Over the carbon film resistor, there is a protective coating of epoxy material or similar insulating material. This protective coating acts as an environment that keeps the resistor away from moisture, dust, and other mechanical influences.

In addition, the coating may also have color bands, which typically indicate the value and tolerance of the resistor itself, relative to resistor color coding standards.

Working

The resistive element is the thin layer of carbon that is deposited on the ceramic substrate. Compared to metals, carbon has relatively greater resistivity; therefore, when current flows through the carbon film, it incurs resistance.

When a battery is connected to a resistor, electrons move from the negative terminal of a battery to the load through a resistor. As they flow through the resistor, the electrons frequently collide with the close packing material atoms. These collisions lead to resistance and could reduce current; this would further convert electrical energy into heat that may eventually be dissipated.

The resistance value of the carbon film resistor is determined by:

• Thickness of the Carbon Film: The thinner film causes an increase in resistance.

• The length of the spiral cut: The greater the length of the present path is the more the resistance becomes.

• Width of the Carbon Path: Narrow path presents with a high resistance.

* Refer Below 3d model to learn how a carbon resistor works