Carbon Resistor


Carbon resistors are a type of resistance component used in electrical and electronic circuits to provide resistance to the flow of electricity, generally as a way to regulate current or voltage. There are multiple types of carbon resistors and each type has different features, functions, and uses that it performs well.

Graphite or coke, for instance, are carbon-based materials used as resistors. The material used in carbon resistors affects their voltage and resistance values, which makes them suitable for use in many different applications like power supplies, circuit breakers, and electric motors. Because of their wide range of values and great stability, carbon resistors are one of the most commonly used types of resistors in electronics today. Let’s take a look at some more specific information about these resistors and what they can do for you and your circuits.

What are Resistors?

The majority of electronic circuit boards contain resistors, which are essential components of electronics. The limit current flow in a circuit by creating resistance to electrons that travel from point A to point B. You could say that resistors are what keep voltage levels in check within an electronic device. They ensure nothing over-heats or explodes—which is definitely a good thing!

Water pressure is similar to that of a water hose. Similar to water flowing through a hose, electrons move through electronic circuits. If you have a small hole at one end of your hose and you open up all of your faucets at once, there will be too much water pressure for that small hole and it will blow out.

Basic Overview of Carbon Resistors

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Carbon resistors are one of several types of resistors. Carbon resistors are made with a thin film of graphite powder and carbon black between two metal plates. The material used in carbon resistors is a conductive polymer called polycarbonate. Polycarbonate allows for efficient conduction of electricity while still maintaining stable electrical characteristics and resisting high temperatures. Because they have relatively low power capacity and high resistance, carbon resistors work best to remove electrical noise or fluctuations from circuits or parts.

For most practical purposes, carbon resistors are used in high-voltage applications. The low-power capacity of carbon resistors makes them ideal for applications that require minimal power consumption. Carbon resistors are also commonly used as voltage dividers because they offer stable resistance over a wide range of voltages and currents. They are especially useful when you need to control current flow from an alternating source, such as an audio amplifier or radio receiver.

Typical Carbon Resistor Components

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Resistors can be constructed from a variety of materials, including carbon. Parts of a carbon resistor include:

  • Ceramic Core: In a carbon resistor, there is an insulating layer on both sides of a wire coil. The ceramic core serves as a bridge for conducting electricity from one end to another end. It also helps in reducing heat loss in resistors.

  • Carbon Film: Carbon film resistors are made of carbon material that has a thin layer of metal on top. This material is designed to handle high temperatures and voltages without breaking down over time.

  • Nickel Cap: Carbon-Film resistors are made with a nickel cap that is baked onto their surface. This helps to protect against oxidation and degradation over time. These resistors offer very high precision at an economical price.

  • Lead: The leads are used to connect a carbon resistor to other components in an electrical circuit. Carbon resistors may be made with or without lead, depending on their application and design requirements. Carbon resistors with leaded ends are typically used for high-power applications such as power supplies and motor control circuits.

  • Protective Lacquer: Protective Lacquer is a lacquer that is applied to carbon resistors in order to prevent them from being oxidized. This is done by applying a protective coating of lacquer to carbon resistors so that they do not react with oxygen or moisture in their environment.

Applications of Carbon Resistor

Carbon resistors are used when very high power and high precision are required. In such cases, no semiconductor device can be used. These have characteristics intermediate between metal-wire and carbon composition resistors. They have a very high level of electrical resistance when they’re in their operating range. This makes them useful for protecting circuits from electric shorts and surges.

Some major applications of Carbon Resistor are:

  • In a dc power supply circuit, carbon resistors are used to adjust the voltage. In an ac power supply circuit, carbon resistors are used to limit current and regulate voltage.

  • They can be used as a voltage divider in some applications.

  • A carbon resistor is used in many other circuits such as motor speed control, lamp dimmer circuits, etc.

  • They are used in X-ray tubes and some high voltage circuits.

  • They can be used as temperature sensors in electronic devices.

Working of Carbon Resistors

Carbon resistors work on a different operating principle than other resistors. Carbon is semi conductive and thus creates a voltage drop across it when electrical current passes through it. The resistance of carbon resistors can be changed by varying their size or shape. The conductivity of carbon can be altered by adding impurities to it or heating/cooling it in certain ways. This makes carbon resistors very versatile in applications where they need to change their resistance with temperature or based on some other factor like light exposure, chemical reaction, etc.


Q1. What is the tolerance of silver strip?

Ans. There is a 10% tolerance on silver strips.

Q2. What is the Symbol of Carbon Resistor?

Ans. It is generally represented by "CR".

Q3. What are the uses of rheostat?

Ans. A rheostat is an electrical device that allows for variable resistance when designing a circuit. Rheostats are mainly used in automobiles.

Q4. What is the power range of a carbon resistor?

Ans. A carbon resistor has a power range of 100mW to 1W.


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