The resistor definition states, that it is a fundamental device used in all electronic devices. The resistor is a passive electrical component with two terminals. As per the definition of the resistor, it is used for restricting the flow of electric current in the circuit. In this article, we’ll go about what a carbon resistor is, as well as its parts and applications.
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What are Carbon Resistors?
Carbon resistors are one of the most common types of electronics used. They are made from a solid cylindrical resistor element with embedded wire leads or metal end caps. Carbon resistors come in different physical sizes with power dissipation limits, commonly from 1 watt down to 1/8 watt.
There are many materials used to produce resistance, particularly metals and alloys like nichrome, brass, platinum and tungsten alloys. However, most of these metals have low electrical resistivity, unlike carbon resistors, which makes it difficult to produce high resistance without becoming bulky. We already know that:
They may, however, give extremely precise resistance measurements and are hence commonly used to calibrate and compare resistances.
For most practical purposes, however, carbon resistors are preferred. This is because they are cheap to produce, compact and can be directly printed onto circuit boards (like the computer processors in phones and tablets). They also reproduce resistance fairly well within practical requirements. Compared to metal wires, which are expensive to produce, carbon is abundantly available, making it cheap. (Ask the price of a resistor in an electronic component store, you can get a dozen for just 2 rupees!).
Parts of a Carbon Resistor
Resistors can be constructed out of a variety of materials. The different parts of a carbon resistor are:
- Ceramic Core
- Nickel Cap
- Lead
- Carbon Film
- Protective Lacquer
The internal structure of a carbon resistor is shown in the image below.
Uses of Carbon Resistors
The carbon resistor contains carbon coated onto a ceramic core. A spiral is etched on the deposited carbon, which turns it into a wire wound on a ceramic core. Depending on the resistance required, pitch, diameter and length of the carbon spiral vary. Nickel caps are attached to both ends of the core so as to create good contact between the carbon and lead. The leads are soldered onto the nickel caps and the entire resistor is coated with lacquer for electrical insulation.
For small resistances required for small currents, the metal caps act as heat sinks to carry away heat dissipated by the resistor. For larger current requirements, a metal heat sink is separately attached to carry away excess heat and to prevent the resistor from burning up.
Carbon resistors are specially colour-coded to identify the resistance.
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Frequently Asked Questions – FAQs
What is the use of a thermistor?
It is employed to translate temperature into electric voltage.
What is the tolerance of gold colour resistance?
The tolerance of gold colour resistance is 5%.
What are the uses of rheostat?
The uses of rheostat are that it can be used as a variable resistor as well as a potential divider.
What is the tolerance of a silver strip?
The tolerance of the silver strip is ±10%.
What is the value of the resistor with colour bands brown, black and red?
The value of the resistor with colour bands brown, black and red is 1000 ohms.
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