Molecular Physics | Thermodynamics Answers

The superconducting transition temperature in a metal is 4.2 K for zero magnetic field. If the magnetic field required to destroy superconductivity at 3.2 K is 0.02T, calculate the critical magnetic field at absolute zero.

For an intrinsic semiconductor with a band gap of 0.75eV, calculate the effective density of states for the electrons and the concentration of electrons in the conduction band at T=300K, given that the effective masses of the electron and hole are equal to the free mass of the electron.

A square lattice has a side of 3.2 Å. Calculate the momentum and energy of an electron whose wave terminates at the boundary of the first Brillouin zone.

The electrical conductivity of monovalent Na metal is 2.17×10^7Ω^(-1)m^(-1). Calculate the relaxation time and the drift velocity in a field of 100 V m^(-1). Take density of Na to be 0.97 gm cm^(-3).

The lattice constant for KCl is 6.292 Å and the Young’s modulus in the [100] direction is 3.2×10^10Nm^(-2). Calculate the force constant and the frequency at which electromagnetic radiation is strongly reflected by the KCl crystal. The atomic weights of K and Cl are 39 amu and 37 amu respectively. Take 1 amu=1.67×10^(-27)kg

The elastic stiffness constants in MgO are as follows:
C_11=2.86×10^11Nm^(-2); C_12=0.87×10^11Nm^(-2); and C_44=1.48×10^11Nm^(-2);
Calculate the velocity of propagation of the longitudinal and transverse elastic waves along the [110] direction in the MgO crystal. Density of MgO is 3.58gcm^(-3)

The net energy of a system of two atoms is given by E(r)={(-A/r^2)+(B/r^8)} where r is the inter-atomic separation. If in a stable molecule the interatomic separation is 0.5 nm and the dissociation energy is 4.0eV, calculate the constants A and B.

Calculate the first order x-ray diffraction angle from the (113) set of planes in fcc platinum which has a lattice parameter of 0.39 nm, given that the wavelength of the x-rays is 0.154 nm

Calculate the atomic packing fraction of the fcc crystal structure.

Determine the boundaries of the first Brillouin zone for potassium which has a bcc structure and a lattice constant of 5.32 Å.