Everything you need to know about Conductors
A substance or material which allows electricity to flow through it is called a conductor or electrical conductor. In a conductor, when voltage is applied, electrical charge carriers (electrons or ions) move effortlessly from one atom to another. Metals like copper are considered good conductors. On the other hand, non metals are usually considered bad conductors (insulators).
The capacity of a substance to transmit electricity or heat is called its conductivity. A conductor is able to conduct electricity because it offers no resistance to the flow of electrons, leading to the flow of electrical current. Metals, metal alloys, water and non metals like graphite are good conductors of electricity. Silver is among the best conductors of electricity. Other good electrical conductors include copper, steel, gold, silver, platinum, aluminum and brass.
You would have noticed that humans are good conductors of electricity, that is why we are advised not to directly touch a person suffering from electrical shock, because we will experience the same shock. In electronic systems, solid metals molded into wires act as conductors or they are etched onto the printed circuit boards.
Characteristics of electrical conductors
An electrical conductor ensures free flow of electrons or ions through its body. A conductor has zero electric field inside it. Outside it, the electric field is perpendicular to the conductor’s surface.
A conductor will have zero charge density. It will ensure that positive and negative charges will cancel each other. This ensures that only free charges exist on the surface.
A major characteristic of a conductor is that it has a low resistance and high thermal conductivity. When placed in a magnetic field, it does not store energy. Both the ends of the conductor will have the same potential. And when potential is changed at one end, electricity starts flowing through the conductor. As a result, electrons start flowing from one end to another.
How do conductors work?
As per the band theory, Solids have both a valence band and a conduction band. A material will be able to conduct electricity through it only if there is no energy gap between its valence band and conduction band. In a conductor, even when a little voltage is applied, these bands overlap, allowing electrons to easily flow through the material. The outer electrons in the valence band are loosely attached to the atom. On applying voltage, the electrons get excited by the electromotive force or the thermal effect. This helps them in moving from the valence band to the conduction band.
Electrons are able to move freely in the conduction band. This results in an abundance of electrons in this particular band. They travel with a to-and-fro motion, and not in a straight line. Their velocity is called drift velocity (Vd). Drift velocity helps electrons in colliding with atoms or other electrons inside the conductor’s conduction band.
Whenever there is a potential difference across two points in the conductor, the electrons tend to flow from the point of lower potency to the point of higher potency. Electrons and electricity will flow in opposite directions. In this case, only a small resistance is offered by the conductor.
Most insulators are solid in nature, they don’t allow electrical current or heat to pass through them. They are also known as dielectric materials. Examples of insulators include wood, fabric, glass, plastic, porcelain and rubber. Most gasses and certain types of distilled water are also good insulators.
All about resistors, semiconductors and superconductors
A resistor is a material which conducts electricity fairly well, but not as good as a conductor. A combination of carbon and clay in a specific ratio is a perfect example of a resistor.
On the other hand, semiconductors act as good conductors under certain conditions and as poor conductors in some other circumstances. The electrons and holes act as charge carriers in semiconductors. Silicon and germanium are examples for semiconductors.
At times, in extremely low temperatures, certain metals conduct electricity better than any known substance at room temperature. This is called superconductivity and a substance which behaves this way is called a superconductor.
Effect of temperature on conductivity
Temperature and conductivity shares an inverse relation. Which means rising temperature will have an adverse impact on conduction. With the rise in temperature, vibration in conductor molecules increases as well. This obstructs the smooth flow of electrons, decreasing the object’s conductivity.
Rising temperatures further might lead to breaking of bonds in conductor materials, resulting in the release of electrons. In this scenario, the material will be left with fewer electrons, reducing its ability to conduct an electrical current through it.
Ohmic conductors and non ohmic conductors
Ohmic conductors strictly follow ohm’s law. In this case, voltage applied is directly proportional to the current flowing. Aluminum, copper and silver are certain examples for ohmic conductors.
Applications of electrical conductors
- Aluminum, being a good conductor of heat and electricity, is widely used for manufacturing cooking utensils.
- Iron being a good conductor of heat, is a major component in manufacturing vehicle engines.
- In automobile radiators, conductors are used to drive away heat from the engine.
Insulators have a wide variety of applications as well. Rubber helps us in manufacturing fire-resistant clothing and footwear. ‘Plastic’ is used for avoiding electrical shock. Insulators protect their users from fire and sound.
Questions and Answers
Check your knowledge
Answer) A substance or material which allows electricity to flow through it is called a conductor or electrical conductor.
Answer) Insulators are substances which do not allow electrical current or heat to pass through them.