what are energy bands ? How are these formed ? Distinguish between conductors and insulators on the basis of formation of these bands. long answer plssss errgant
Answers
Answer:
Explanation:
An energy band is a range of electron energy in a solid so dense with electron states that it appears to be continuous. Energy bands are at the heart of electronic band structure which holds that there are stationary states of electrons in a solid with well defined, constant (quantized) energy.
Each band is formed due to the splitting of one or more atomic energy levels. Therefore, the minimum number of states in a band equals twice the number of atoms in the material. The reason for the factor of two is that every energy level can contain two electrons with opposite spin.
According to the energy band theory the insulators are those materials in which there is a large energy difference between valence and conduction band. The conduction band is empty, and the electrons in the valence band acquire a large amount of energy to jump in conduction band and become free. The forbidden gap is very large between valence and conduction band. That’s why the insulators did not conduct. The electric current is defined as the flow charge and there are no free electrons or holes in insulators so no current flows.
Conductors are the materials or substances which allow electricity to flow through them. They are able to conduct electricity because they allow electrons to flow inside them very easily. Conductors have this property of allowing the transition of heat or light from one source to another.
Metals, humans, earth, and animal bodies are all conductors. This is the reason we get electric shocks! The main reason is that being a good conductor, our human body allows a resistance-free path for the current to flow from wire to our body.
Conductors have free electrons on its surface which allows current to pass through. This is the reason why conductors are able to conduct electricity.
An electrical insulator is a material whose internal electric charges do not flow freely; very little electric current will flow through it under the influence of an electric field. This contrasts with other materials, semiconductors and conductors, which conduct electric current more easily. The property that distinguishes an insulator is its resistivity; insulators have higher resistivity than semiconductors or conductors. The most common examples are non-metals.
A perfect insulator does not exist because even insulators contain small numbers of mobile charges (charge carriers) which can carry current. In addition, all insulators become electrically conductive when a sufficiently large voltage is applied that the electric field tears electrons away from the atoms. This is known as the breakdown voltage of an insulator. Some materials such as glass, paper and Teflon, which have high resistivity, are very good electrical insulators. A much larger class of materials, even though they may have lower bulk resistivity, are still good enough to prevent significant current from flowing at normally used voltages, and thus are employed as insulation for electrical wiring and cables. Examples include rubber-like polymers and most plastics which can be thermoset or thermoplastic in nature.
Insulators are used in electrical equipment to support and separate electrical conductors without allowing current through themselves. An insulating material used in bulk to wrap electrical cables or other equipment is called insulation. The term insulator is also used more specifically to refer to insulating supports used to attach electric power distribution or transmission lines to utility poles and transmission towers. They support the weight of the suspended wires without allowing the current to flow through the tower to ground.
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