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The transfer of heat energy between two things that are in contact is known as conduction. Conduction takes place when particles of solids, liquids, and gases collide with one another. Similarly, because the particles of gases are farthest apart, solids have the slowest conduction.
Conduction
When two objects of differing temperatures come into contact with each other, conduction happens. Heat is transferred from the warmer object to cooler object until they are at the same temperature. The flow of heat through a substance caused by the collision of molecules is known as conduction.
Solids and liquids, where the particles are closer together, conduct more readily than gases, where the particles are more apart.
Conduction occurs in solids, liquids, and gases in all three states of matter. The best conductors are solids, while the worst are gases.
Solid
A solid is defined as a type of substance that undergoes rigidity processing and hence has a fixed shape and volume. Solids contain a regular order of constituent particles, according to the kinetic molecular model. Because they are kept together by rather strong forces, these particles are present in fixed places.
Electrical Conduction In Solids
Conduction is the only way to transmit heat in solids.
When a solid’s one end is heated, the solid’s particles gain kinetic energy. This indicates that they are moving at a faster rate.
The particles in a solid are kept together by strong attraction forces. The particles can only move forward and backward by vibrating forward and backward.
The quantity by which the particles vibrate increases as the substance is heated. This is what it means when you say the solid’s particles have gained kinetic energy.
The extra energy (heat) is passed on to the next particle, which begins to vibrate faster.
Band Theory of Solids
This is the classical theory of electrical and thermal conduction in solids.
The quantum state which is acquire by electron inside a metal solid is described by the band theory of solids. Every molecule has a number of different energy levels. The behaviour of electrons within a molecule is well explained by band theory. The knowledge gathered during the quantum revolution in physics was used to build Band Theory. Felix Bloch applied quantum theory to solids in 1928.
According to Pauli’s exclusion principle, electrons are filled in their respective energy orbits in atoms. A molecular orbit with two separate energy levels is formed when two atomic orbitals join.
1023 stacked lines contained in a small space would resemble a band in solids. As a result, an energy continuum known as energy bands is formed. By showing possible energies for an electron in a material, band theory helps to visualise the distinction between conductor, semiconductor, and insulator.
Valence Band
The valence band is on the bottom. It represents the energy levels nearest to the atom’s nucleus, and the energy levels in the valence band contain the requisite number of electrons to balance the nucleus’ positive charge. As a result, this band is known as the filled band.
Electrons are strongly linked to the nucleus in the valence band. As you progress up the energy scale, the electrons become less tightly coupled as they approach the nucleus. It’s difficult to disturb electrons at higher energy levels near the nucleus since their mobility necessitates higher energies and each electron orbit has its own energy level.
Conduction Band
The conduction band is the top or outermost band in the energy level diagram. An electron conducts electric current if its energy level falls inside this band and it is relatively free to roam about in the crystal.
The valence and conduction bands are the most important in semiconductor devices.
Forbidden Gap
The forbidden band, often known as the forbidden gap, is the energy gap between the valence band and the conduction band. The forbidden gap, as well as the classification of materials as conductors, semiconductors, and insulators, define the electrical conductivity of a solid.
The breadth of the prohibited gap can be used to determine a material’s conduction condition. The breadth of the gap is measured in electron volts in atomic theory (eV). When an electron is exposed to a potential difference of 1 V, an electron volt is defined as the amount of energy acquired or lost. Each element’s atoms have a different energy-level value, which allows for conduction.
Difference Between Conduction of Electricity in Solids and Liquids
There are following differences between conduction of electricity in solids and liquids which are given here.
- Electricity is transmitted by electrons in solids, but it is carried by ions in liquids (positively charged ions and negatively charged ions).
- Electricity is carried by electrons in a solid like copper metal, but electricity is carried by copper ions and sulphate ions in a liquid like copper sulphate solution.
- When electricity passes through a solid, no chemical change occurs; but, when electricity passes through a liquid, a chemical change occurs.
Conclusion
The transfer of heat energy between two things that are in contact is known as conduction.
Conduction occurs in solids, liquids, and gases in all three states of matter.
The best conductors are solids, while the worst are gases.
Conduction is the only way to transmit heat in solids.
According to Pauli’s exclusion principle, electrons are filled in their respective energy orbits in atoms.
Valence band represents the energy levels nearest to the atom’s nucleus.
When electricity passes through a solid, no chemical change occurs; but, when electricity passes through a liquid, a chemical change occurs.
