An electrical conductor is a material that facilitates the flow of electricity. Within these substances, charge carriers, predominantly electrons or charged ions, transfer easily from one atom to another when a voltage is applied. Generally, metals, particularly copper, are recognized as excellent conductors, while nonmetals serve as insulators, hindering electric flow.
Understanding Electrical Conductors
Conductivity reflects a material’s ability to transmit electric current or heat. Effective conductors permit the unrestricted movement of electricity, posing minimal resistance to electron flow, which results in high electrical current. Substances like metals, metal alloys, electrolytes, and certain nonmetals, such as graphite, exhibit good conductivity. Notably, pure silver ranks among the best conductors.
- Copper
- Steel
- Gold
- Silver
- Platinum
- Aluminum
- Brass
While pure water is an insulator, adding even a small amount of salt converts it into an excellent conductor. Human bodies, primarily composed of water, can also conduct electricity, which is why contact with someone experiencing an electric shock can transmit the shock.
In the realm of electronics, conductors are commonly fashioned into wires or etched onto printed circuit boards. Even though all normal conductors exhibit some degree of resistance, excessive current can generate heat, posing a fire risk. Conversely, superconductors exhibit no resistance, enabling them to carry unlimited electrical current.
Key Characteristics of Electrical Conductors
Key attributes of electrical conductors include:
- Facilitation of free movement for electrons or ions
- Absence of an internal electric field, allowing unhindered electron flow
- An external electric field that is perpendicular to the conductor’s surface
- Zero charge density, ensuring cancellation of positive and negative charges, with free charges only on the surface
Conductors also possess low resistance and high thermal conductivity. Notably, conductors maintain the same electric potential at both ends, enabling electric flow when a potential difference is introduced.
How Conductors Work
The electron energy band theory in solid-state physics suggests that for electrical current flow, there should be no energy gap between the valence and conduction bands of a material. In conductors, these bands overlap, allowing electrons to move even under minimal voltage. The outer electrons in the valence band are loosely bound, making them susceptible to excitation from voltage, thermal energy, or electromotive force, resulting in their movement to the conduction band.
In the conduction band, these electrons can navigate freely, exhibiting a to-and-fro motion known as drift velocity. This drift allows for collisions with atoms or other electrons, facilitating current flow from lower to higher potential points across the conductor. It’s essential to note that while it might seem like individual electrons traverse the entire circuit, they actually shift between atoms, which is especially relevant in alternating current (AC) systems where electrons oscillate rapidly.
What Are Insulators?
Insulators are materials that resist the passage of electrical current or heat. These dielectric materials are predominantly solid and include:
- Wood
- Fabric
- Glass
- Quartz
- Mica
- Plastic
- Porcelain
- Rubber
Many gases and certain types of distilled water also exhibit good insulating properties.
Resistors, Semiconductors, Superconductors, and Ionic Conductors
Resistors are materials that conduct electricity well but not as efficiently as conductors. A common example is a mixture of carbon and clay, which provides a consistent resistance to current. All regular conductors have inherent resistance.
Semiconductors, like silicon and germanium, act as effective conductors under specific conditions while performing poorly under others. In semiconductors, both electrons and absence of electrons (holes) serve as charge carriers.
Superconductivity, observed at very low temperatures, enables certain materials to conduct electricity without resistance, marking them as superconductors. Ionic conductors, often liquid solutions embedding ions, facilitate charge transmission and are integral in devices such as capacitors and batteries, notably lithium-ion batteries.
Temperature’s Effects on Conductivity
Conductivity inversely correlates with temperature; as temperature rises, the vibration of molecules in conductors increases, hindering electron flow and reducing conductivity. Elevated temperatures can also disrupt molecular bonds, releasing electrons and diminishing the conductor’s capacity to transmit electric current.
Types of Conductors
Conductors can be categorized based on their ohmic response:
- Ohmic conductors – adhere to Ohm’s law, where voltage is proportional to current (e.g., aluminum, copper, silver)
- Nonohmic conductors – do not follow Ohm’s law (e.g., thermistors, photoresistors)
Electrical Conductor Applications
Conductors find numerous applications, including:
- Silver – while an exceptional conductor, its cost limits its use to specialized scientific equipment
- Copper – a widely used conductor whose rising cost has led to its limited use in smaller applications
- Aluminum – favored for its cost-effectiveness in wiring
- Gold – best known for being highly conductive despite its high price, often used in connectors
- Iron – used for its conductive properties in vehicle engine manufacturing
- Automobile radiators – employ conductors to dissipate engine heat
Insulators also serve various applications, such as rubber for manufacturing fire-resistant clothing and plastic in electrical devices to protect users from electric shocks, as well as providing insulation against fire and sound.