List of practice Questions

For temperature greater than 0 K, the fermi level is the level where the probability of occupation of electrons is:
According to the Bloch theorem, which of the following equations is the correct form for Bloch functions:
In the Kronig penny Model, the energy of the lowest band at wave vector k = 0 is given by \( E = \frac{h^2 P}{4\pi^2 m a^2} \). This value of energy holds for which condition of Kronig penny potential (P):
Choose the correct statement for the first Brillouin zone in two dimensions:
A. The region in k space that the electrons can occupy without being diffracted is called the First Brillouin zone.
B. For k<\(\pi\)/a electrons can not move freely in any direction inside the square without being diffracted.
C. For k = \(\pi\)/a electrons are prevented from moving in the x or y directions due to diffraction.
D. For k>\(\pi\)/a electrons can move perpendicularly inside the square.
Choose the correct answer from the options given below:
The effective mass of an electron is ______________________________ in the lower part of the band and ______________________________ near the zone boundary (k\(\sim\)\(\pi\)/a).
The density of zinc is \(7.13 \times 10^3\) kg/m\(^3\) and its atomic weight is 65.4. The fermi energy of Zinc is:
(Given that the effective mass of the electron in zinc is \(0.85m_e\))
In 3-dimensional system, the mean energy of an electron in electron gas at absolute zero is __________________________ of fermi energy, \(E_f(0)\) at absolute zero.
Which of the following statements are correct for the Sommerfeld model:
A. The free electrons are valence electrons of the composing atoms.
B. The potential energy of an electron at rest inside the metal is assumed to be higher than that of an electron outside the metal.
C. In this model, the mutual repulsion between the electrons is neglected.
D. The potential energy for an electron is periodic.
Choose the correct answer from the options given below:
Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A): In the absence of an electric field, the electron gas is in an equilibrium state described by equilibrium distribution functions, viz the fermi-Dirac distribution function for a degenerate electron gas and Maxwell-Boltzmann distribution function for a non-degenerate electron gas.
Reason (R): In a conductor, the number of electrons moving in opposite directions is always the same, their average velocity in any direction is zero and consequently, the distribution functions are symmetric about the axis of ordinates.
In light of the above statements, choose the correct answer from the options given below.
According to Weidemann-Franz-Lorentz Law, the theoretical value of Lorentz number (L) for metals is:
The effective density of states of electrons (\(N_c\)) at the conduction band edge of the intrinsic semiconductor varies with temperature, as:
Which statements are true about wave propagation through a medium:
A. Frequency changes in a non-linear medium but remains constant in a linear medium.
B. Frequency changes in a linear medium but remains constant in a non-linear medium.
C. R + T = 1, where R is the reflection coefficient and T is the transmission coefficient
D. R + T $>$ 1, where R is the reflection coefficient and T is the transmission coefficient
Choose the correct answer from the options given below:
Paramagnetic materials behaves as diamagnetic materials :
What is the effect of temperature on magnetic susceptibility of ferromagnetic materials?
Domain theory explains:
Antiferromagnetic materials have magnetic susceptibility in the range:
Which of the following is true for hard magnetic materials:
The speed of sound in a fluid is the velocity at which a weak pressure wave propagates in the medium.
The ideal gas, which is a model for gas used in constant volume gas thermometers, for which P = \(\rho\)RT. This equation illustrates that there are only ______________________ independent intensive thermodynamic properties for a simple fluid.
The breaking stress of a wire depends on:
Under the elastic limit, Poisson's ratio is:
The elastic energy density of a stretched wire is given by:
Which of the following option is correct related to the application of elastic hysteresis?
Which statements are true for total internal reflection?
A. The angle of incidence must be greater than the critical angle
B. light goes from an optically denser medium to an optically rarer medium.
C. light goes from an optically rarer medium to an optically denser medium.
D. The critical angle depends on the refractive index of both media.
Choose the correct answer from the options given below:
Which of the following are the correct statements about laws of thermodynamics:
A. The first law does not indicate the direction in which the change can occur.
B. The first law indicates the direction in which the change can occur.
C. The second law does not indicate the direction in which the change occurs.
D. The second law indicates the direction in which the change can occur.
Choose the correct answer from the options given below: