Beatrice Lang
Conductors are materials that allow electricity to flow through them easily. They have a very low resistance to electrical current. Metals are common electrical conductors, with silver, copper, gold, and aluminium being the best metal conductors. The more free electrons present in a metal, the greater its conductivity. However, the shape and size of a material, its temperature, and the presence of impurities can also affect its conductivity. Insulators, on the other hand, are non-conducting materials with few mobile charges that support only insignificant electric currents.
| Characteristics | Values |
|---|---|
| Definition | An object or type of material that allows the flow of charge (electric current) in one or more directions |
| Conductivity | Depends on the material and its dimensions, e.g. thickness, length, temperature, and electromagnetic field |
| Material | Metals such as copper, aluminium, silver, and gold. Non-metallic conductors include graphite, conductive polymers, and electrolytes. |
| Resistance | Conductors have low resistance to electrical current. Resistance is inversely proportional to the cross-sectional area and proportional to the length. |
| Electrons | Conductors have free electrons that can move easily when connected to a power source. |
| Insulators | Non-conducting materials with high resistance to electrical current, e.g. glass, plastic, rubber, and wood. |
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What You'll Learn
Metals are good conductors
Additionally, the crystal structure of metals plays a role in their conductivity. Metals typically have a crystalline structure characterized by a close-packed arrangement of atoms with high symmetry. This structure enables the easy movement of valence electrons, further enhancing their conductivity.
The purity and chemical composition of a metal also influence its conductivity. Impurities within a metal can hinder the flow of electrons, reducing its effectiveness as a conductor. Common metallic conductors include copper, aluminum, gold, and silver, with silver being the best electrical conductor under ordinary temperature and pressure conditions.
It is worth noting that while most metals are good conductors, their conductivity can be affected by factors such as temperature and shape. Metals generally conduct better when cool, and thicker pieces of metal conduct better than thinner ones due to reduced resistance. However, temperature can also impact the geometry of the conductor, influencing its resistance and, consequently, its conductivity.
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Temperature affects conductivity
Temperature has a significant effect on the efficacy of conductors. Materials may expand under the application of heat, and the amount they expand is governed by their thermal expansion coefficient. This expansion or contraction changes the geometry of the conductor and, therefore, its characteristic resistance. However, this effect is generally small.
An increase in temperature will also increase the number of phonons generated within the material. Phonons are essentially lattice vibrations or small, harmonic kinetic movements of the atoms of the material. They disrupt the path of electrons, causing them to scatter, which decreases the number of electron collisions and the total amount of current transferred.
In metal conductors, increasing the temperature usually results in a decrease in conductivity or an increase in resistivity. As the temperature rises in metals, the positive ions inside the metal conductor vibrate more, and the thermal speed of the electrons increases, resulting in increased resistance and decreased conductivity. Metals are better conductors when cool and less efficient when hot.
In contrast, the electrical conductivity of semiconductors increases as temperature increases. As the temperature rises, electrons from the valence band are able to jump to the conduction band, creating free movement between the two bands and increasing conductivity. This movement of electrons creates an electrical current. Some insulators, like glass, are poor conductors when cool but become good conductors when hot.
Conductivity invariability increases with temperature increases, and conductivity levels depend on ion mobility, the valence of the ions, and temperature. When the temperature in a solution increases, viscosity decreases, and ion mobility increases, which directly affects the conductivity of metals and solutions.
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Insulators vs conductors
Conductors are materials that allow electricity or electric current to pass through them. They are defined by their ability to allow an easy flow of electrons within them from one atom to another. This property is known as conductivity. Materials made of metal are common electrical conductors, with the flow of negatively charged electrons generating electric current. Some common conductors are copper, aluminium, gold, and silver. Copper is a great electrical conductor and is commonly used, while aluminium is the most common metal in electric power transmission and distribution. Other materials sometimes used as conductors include silver, gold, and aluminium.
Insulators, on the other hand, are non-conducting materials with few mobile charges that support only insignificant electric currents. They do not allow electricity or electric current to flow through them as they do not promote the free flow of electrons from one atom to another. Insulators are used to protect us from the dangerous effects of electricity flowing through conductors. Some common insulator materials are glass, plastic, rubber, air, and wood. Power cords are a great example of how conductors and insulators work together. The inside of a power cord is made of copper wires so that electricity can flow, while the outside is made of rubber, insulating the wires and stopping the flow of electricity to places it shouldn't go, such as our hands.
The shape and size of a material affect its conductivity. For example, a thick piece of matter will conduct better than a thin piece of the same size and length. If you have two pieces of the same thickness, the shorter one will conduct better because it has less resistance. Temperature also affects conductivity. As temperature increases, atoms and their electrons gain energy. Some insulators like glass are poor conductors when cool but good conductors when hot, while most metals are better conductors when cool and less efficient when hot.
Some materials in pure form are insulators but will conduct if they are doped with small quantities of another element or if they contain impurities. For example, most ceramics are excellent insulators but doping them can create a superconductor. Similarly, pure water is an insulator, dirty water conducts weakly, and saltwater, with its free-floating ions, conducts well.
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Superconductors
Materials that are good conductors of electricity include most metals, electrolytes, superconductors, semiconductors, plasmas, and some non-metallic conductors like graphite and conductive polymers.
Superconductivity is a set of physical properties observed in superconductors, which are materials where electrical resistance vanishes and magnetic fields are expelled. Superconductors are unique in that their resistance drops abruptly to zero when they are cooled below a critical temperature, whereas the resistance of ordinary metallic conductors decreases gradually as the temperature is lowered. This critical temperature varies depending on the material, and some materials, known as high-temperature superconductors, can be superconducting at temperatures above liquid nitrogen.
The phenomenon of superconductivity was discovered in 1911 by Dutch physicist Heike Kamerlingh Onnes, who observed it in mercury cooled to cryogenic temperatures. Soon after, Kamerlingh Onnes attempted to make an electromagnet with superconducting windings but found that relatively low magnetic fields destroyed superconductivity. However, in 1955, G. B. Yntema successfully constructed a small iron-core electromagnet with superconducting niobium wire windings.
In 1933, Meissner and Ochsenfeld discovered that superconductors expelled applied magnetic fields, a phenomenon known as the Meissner effect. The Meissner effect was later explained by Fritz and Heinz London in 1935, who showed that it was due to the minimization of the electromagnetic free energy carried by the superconducting current.
In 1986, scientists discovered a new class of copper-oxide materials that exhibited superconductivity at much higher temperatures than previously observed. These materials, known as high-temperature superconductors, have led to the discovery of many new superconducting materials using educated guesses and trial-and-error experiments.
More recently, MIT physicists discovered a new type of superconductor that also exhibits magnetic properties, known as a chiral superconductor. This discovery was made in rhombohedral graphene cooled to extremely low temperatures, and it challenges the previous belief that magnetism and superconductivity could not coexist in a single material.
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Conductor materials
Metals are common electrical conductors. The flow of negatively charged electrons generates electric current, positively charged holes, and positive or negative ions in some cases. Electrons are the primary mover in metals, and the more free electrons present in a metal, the greater its conductivity. Silver is the best conductor of electricity because it contains a higher number of movable atoms (free electrons). However, silver is expensive and not normally used unless required for specialized equipment. Copper is the next best conductor and is a very good conductor of electrical current. It is also inexpensive when compared to silver and gold, making it the most popular material used for wires. Copper is also easy to solder and wrap into wires, so it is often used when a large amount of conductive material is required.
Other metals that can act as conductors include gold, aluminium, and stainless steel. Gold is a good electrical conductor and does not tarnish when exposed to the air, but it is too expensive for common use. Aluminium is a good conductor with conductivity slightly less than copper, and it is used in the home's internal wiring, often in combination with copper. Stainless steel is also a relatively good conductor of electricity.
Some non-metallic conductors include graphite, conductive polymers, superconductors, semiconductors, and plasmas. For example, carbon in the form of graphite is an excellent conductor of electricity because only three of the four carbon atoms are used for bonding.
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Frequently asked questions
Electrical conductors are objects or materials that allow the flow of electric charge or current.
Metals are common electrical conductors, with the best conductors being silver, copper, and gold. Other conductive materials include electrolytes, superconductors, semiconductors, plasmas, and non-metallic conductors like graphite and conductive polymers.
Electrical wires, electric plugs, and the internal mechanisms of electric irons are all made with metal conductors. Copper is the most popular material for wires due to its conductivity and low cost.
The shape, size, and temperature of a material can all impact its conductivity. For instance, a thick piece of material will conduct better than a thin piece of the same size and length. Additionally, increasing the temperature of a conductor generally decreases its conductivity.
Conductors have low resistance to electrical current due to their free movement of electrons, while insulators have high resistance as their electrons are tightly bound and do not allow the flow of electrons. Common insulators include glass, plastic, rubber, air, and wood.
