Otis Singleton
Materials through which electricity cannot pass are known as insulators. Insulators are materials that do not conduct electricity, such as paper, plastic, rubber, glass, and air. The electrons in insulators are so tightly bonded that there are no free electrons available to carry a current. Insulators are used to prevent electrical conductors from coming into unintentional contact with each other.
| Characteristics | Values |
|---|---|
| Name | Insulators |
| Examples | Paper, plastic, rubber, glass, wood, and air |
| Material property | Electrons are firmly bonded and unavailable for mobility |
| Comparison with porcelain insulators | Cheaper, higher tensile strength, higher dielectric strength, longer service life |
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What You'll Learn
Insulators, such as glass, prevent electricity flow
Materials that electricity cannot pass through are known as insulators. Insulators are materials that do not conduct electricity. They are typically rated in the hundreds of volts range, while certain power distribution insulators can be rated in the hundreds of thousands of volts range. Insulators have a high resistivity, which means they prevent the flow of electric current.
The atoms of the insulator have tightly bound electrons, which cannot move freely. This is because the electrons in insulators are so firmly bonded to one another that no free electrons are available for mobility. As a result, they are unable to conduct electricity. In contrast, the outer electrons of conductive materials are free to move, allowing the flow of electricity.
Insulators are used to prevent electrical conductors from coming into unintentional contact with each other. For example, an insulator is installed between a grounded supporting tower or pole and a current-carrying conductor to prevent current from flowing from the conductor to the earth. In electrical wiring, an insulator coating is often applied to wires and cables to prevent short circuits and fire hazards.
It is important to note that a perfect insulator does not exist because even insulators contain small numbers of mobile charges that can carry a current. Additionally, all insulators can become electrically conductive when a sufficiently large voltage is applied, causing an electrical breakdown.
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Paper, plastic, rubber, and wood are also insulators
Materials that electricity cannot pass through are known as insulators. Insulators have a high resistivity, meaning that their atoms have tightly bound electrons which cannot move freely. As a result, electricity cannot flow through them.
Paper, plastic, rubber, and wood are all insulators. Paper, for instance, is used in large power transformer windings, often alongside wood, varnish, and mineral oil. Plastic is also used in electrical insulation, with flexible plastics like PVC being employed to insulate circuits and prevent human contact with live wires.
Rubber is another insulator, with silicone rubber being used in composite insulators. These are made of a central rod of fibre-reinforced plastic and an outer weathershed of silicone rubber. Wood is also used in transformers, with large power transformer windings being insulated with wood.
Other insulators include glass, air, and vacuum. Insulators are important in electrical systems to prevent electrical conductors from coming into contact with each other unintentionally.
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Insulators have a high resistance
Materials that electricity cannot pass through are known as insulators. They have high resistance, which means it is difficult for electric charges to flow through them. Insulators include materials such as rubber, glass, paper, plastic, and wood. The electrons in these materials are firmly bonded, leaving no free electrons for mobility, and thus they are unable to conduct electricity.
Insulators are used to protect and support electrical systems, while conductors are used to make wires and circuits. An example of an insulator in this context is the rubber used in electrical cables to prevent electric shock. On the other hand, copper wiring, a conductor, is used in household electrical circuits to facilitate the flow of electricity.
The difference between insulators and conductors is crucial when designing electrical systems. While insulators have high resistance, conductors have low resistance. This means that insulators do not allow electric current to pass through easily, whereas conductors permit the flow of electric current with relative ease.
It is important to note that when the electric field applied across an insulator exceeds the threshold breakdown field, the insulator becomes a conductor. This occurs when the electric field accelerates free charge carriers to a velocity that can knock electrons from atoms, creating a chain reaction that fills the insulator with mobile charge carriers and reduces its resistance.
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Insulators have a low thermal expansion coefficient
Materials that electricity cannot pass through are known as insulators. Insulators include materials such as paper, plastic, rubber, glass, and air. Insulators have firmly bonded electrons, leaving no free electrons available for mobility, thus making them unable to conduct electricity.
Materials with low thermal expansion coefficients, such as insulators, do not expand significantly when heated. Crystals tend to have the lowest thermal expansion coefficients due to their uniform and structurally sound lattice structure. Diamond, for example, has the lowest known thermal expansion coefficient of all naturally occurring materials.
In contrast, materials with weak inter-molecular bonds, typically polymers, have high thermal expansion coefficients. These materials also tend to have low melting points, as weaker bonds are more easily overcome with the vibrational energy from heat. While metals tend to have relatively low thermal expansion coefficients, they are still susceptible to expansion and can experience material failure due to expansion stress.
The low thermal expansion coefficient of insulators is advantageous in various applications. For example, glass insulators are used in transmission and distribution networks due to their high dielectric strength, long service life, and low cost compared to porcelain insulators. Understanding the thermal expansion properties of materials is crucial in designing factories and products to prevent structural damage caused by thermal expansion.
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Insulators are poor conductors of electricity
Materials that electricity cannot pass through are known as insulators. Insulators are materials that do not conduct electricity. They are poor conductors of electricity because they have fewer mobile charge carriers, which results in higher resistivity. This means that for a given current, insulators will get hotter.
The ability of a material to conduct electricity depends on how easily electrons can move through it. Insulators have electrons that are firmly bonded to one another, leaving no free electrons available for mobility. This is due to the presence of strong covalent bonds in their molecular structure, which prevents the movement of electrons and, therefore, electrical conduction.
Examples of insulators include glass, rubber, wood, plastics, paper, and air. Insulators are often used to coat electrical conductors or provide a barrier between them to control electric currents, such as in rubber-coated wires and cables.
It is important to note that some materials may act as insulators in their pure form but can become conductors when doped with small quantities of another element or when they contain impurities. For instance, pure water is an insulator, while dirty water conducts weakly, and saltwater, due to its free-floating ions, conducts well.
Additionally, the shape, size, and temperature of a material can also affect its conductivity. For example, a thick piece of material will conduct better than a thin piece of the same size and length. Similarly, some insulators, like glass, are poor conductors when cool but become good conductors when hot.
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Frequently asked questions
Materials that electricity cannot pass through easily are known as insulators.
Insulators include materials such as glass, rubber, wood, plastics, paper, and air.
The electrons in insulators are so firmly bonded to one another that no free electrons are available for mobility, and as a result, they are unable to conduct electricity.
