Band thoery , effective mass and concept of holes

What is the primary assumption of the tight binding model?

• Electrons are free to move throughout the material.

• Electrons are loosely bound to their atoms.

• Electrons do not interact with their surrounding environment.

• Electrons are tightly bound to their atoms.

How does the tight binding model describe electron behavior in solids?

• Electrons are described as free particles with no interaction in the tight binding model.

• The tight binding model describes electron behavior in solids by using overlapping atomic orbitals to form energy bands.

• Electrons are treated as localized particles with fixed positions in the tight binding model.

• The tight binding model uses classical mechanics to explain electron motion in solids.

Define the density of states in the context of solid-state physics.

• The density of states indicates the total number of atoms in a solid.

• The density of states refers to the total mass of a solid per unit volume.

• The density of states is the measure of temperature variation in a solid.

• The density of states is the measure of number of occupied orbitals per unit energy level

What is the significance of the density of states in electronic properties?

• The density of states is significant as it determines the availability of electronic states for conduction and influences the material's electronic properties.

• It determines the mechanical strength of the material.

• It indicates the color of the material.

• It measures the temperature of the material.

List one application of the tight binding model in material science.

• Predicting electronic band structure in crystalline solids.

• Calculating thermal conductivity in metals.

• Analyzing magnetic properties of insulators.

• Determining crystal lattice parameters.

How can the tight binding model be used to explain band structure?

• The tight binding model explains band structure by showing how atomic orbitals overlap to form energy bands in a solid.

• It focuses solely on the temperature dependence of conductivity in materials.

• It illustrates the effects of external magnetic fields on electron motion.

• It describes how electrons are added to a solid without considering atomic interactions.

Explain how the tight binding approximation can be applied to semiconductors.

• It describes the thermal properties of semiconductors.

• It focuses on the magnetic properties of metals.

• The tight binding approximation models the electronic band structure of semiconductors by considering atomic orbital overlaps and electron hopping between neighboring sites.

• It analyzes the optical properties of insulators.

The fermi radius is directly proportional to

• N^1/2

• N^2/3

• N^1/3

• N^3/2

The density of states for a bulk system is found to be

• directly proportional to E^1/2

• directly proportional to E^3/2

• inversely proportional to E^3/2

• inversely proportional to E^1/2

As per band theory, which electrons act as free electrons?

• Electrons nearer to nuclei having lesser potential energy.

• Electrons nearer to nuclei having higher potential energy.

• Electrons farther away from nuclei having maximum potential energy

• Electrons farther away from nuclei having minimum potential energy