CONDENSED MATTER PHYSICS (PREVIOUS SET QUESTIONS)

 Condensed Matter Physics 

 Bravais Lattices, Reciprocal lattice, Diffraction and the structure factor. Bonding of solids, Elastic properties, phonons, lattice specific heat. Free electron theory and electronic specific heat. Response and relaxation phenomena. Drude model of electrical and thermal conductivity. Hall effect and thermoelectric power. Electron motion in a periodic potential, band theory of solids: metals, insulators and semiconductors, First and second order phase transitions. Diamagnetism, Paramagnetism and ferromagnetism, Superconductivity: type1 and type 2 superconductors, Josephson junctions. Superfluidity. Defects and dislocations Ordered phases of matter: translational and orientational order, kinds of liquid crystalline order. Quasi crystals.

PREVIOUS YEAR QUESTION PAPER

SET 2019/7

42. The temperature of the antiferromagnetic -to- paramagnetic transition is called:

A) Debye temperature          B) Neel temperature

C) Curie - Weiss temperature D) None of the above

43. The magnetic susceptibility of a super conductor is

A) +1    B) 0     C) -1     D) None of these

48. The conductivity of a semiconductor can be written as -

A) CONDUCTIVIT=(neeme+nhemh)

#me= mue of electron, #mh=mue 

49. In a superconducting state -

A) Entropy increases & thermal conductivity decreases

B) Entropy & thermal conductivity decreases

C) Entropy & thermal conductivity increases

D) Entropy decreases & thermal conductivity increases

74. Crystal structure of NaCl is ------.

A) simple cubic B) hexagonal C) body centered cubic D) face centered cubic

75. Which among the following is a correct statement of Laue’s theorem?

A) Δk = G     B) 2k .G + G2 = 0   C) both A and B     D) none of these

76. In a one dimensional diatomic lattice, both the atoms vibrate against each other with their

centre of gravity fixed for ------.

A) acoustic mode B) optical mode

C) transverse acoustic mode D) none of these

77. Low temperature lattice specific heat capacity of solids is explained by -----.

A) Einstein’s theory of specific heat     B) Bloch theorem

C) Debye theory of specific heat           D) London theory

78. Tunnelling of Cooper pairs at ------is called Josephoson effect.

A) superconductor-superconductor

B) n-semiconductor-p-type semiconductor

C) superconductor-insulator-superconductor

D) superconductor-semiconductor

79. For an n-type semiconductor at ordinary temperatures, the Fermi level is --------.

A) exactly at the centre of the forbidden energy gap

B) closer to the conduction band

C) closer to the valence band

D) within the valence band

80. In the case of a ferroelectric crystal which among the following is TRUE?

A) it has electric dipole moment only when an external electric field is applied

B) centre of positive charge and centre of negative charge will coincide

C) electric dipole moment is temperature dependent

D) specific heat is temperature independent

81. Ferromagnetic crystals show magnetic hysteresis due to -------.

A) the presence of magnetic domains

B) the presence of uncompensated surface moments

C) the electron-phonon interaction

D) electron-nucleus interaction

92. The direct evidence for the existence of magnetic moments of atoms and their space

quantization is provided by the ---- experiment.

A) Davisson and Germer     B) Hall effect

C) Stern -Gerlach                 D) Stark effect

94. Which of the following is Fermi’s Golden rule?

A) w= [2pi/hcut]/H'kn/^2 *ro(Ek)

SET 2019/2

19. The co-ordination number of a face centered cubic structure is

A) 8       B) 6         C) 4      D) 12

20. If the primitive cell contains p atoms, then the number of optical branches in the phonon

dispersion relation is

A) 3p-1       B) 3p-2        C) 3p-3      D) 3p

21. The specific heat capacity of a material at very low temperature varies with temperature T as:

 C) Cv  propotional to T^3

22. If K and σ are the thermal and electrical conductivities of a metal at temperature T, then Lorentz number (L) can be represented as:

 B) K/Tσ 

23. The magnetic state of a superconductor is:

A) Paramagnetic    B) Diamagnetic  C) Ferromagnetic      D) Antiferromagnetic

24. The critical magnetic fields of a superconductor material are 1x105 A/m and 2x10^5 A/m at  10 K and 0 K respectively. Then, the critical temperature of the material is

A) 10.31 K   B) 10 K    C) 14.14 K    D) 7.07 K

28. The momentum of a phonon is

A) ћk B) ћω C) Zero D) hk

29. The frequency of electromagnetic wave radiated by a Josephson junction when a DC  voltage of 6.63 μV is applied across the junction is

A) 1.6 MHz  B) 3.2 GHz   C) 6.63 GHz    D) 1.6 GHz

31. The relative permeability of a material X is slightly less than unity and that of a material Y is

very much larger than unity. Then,

A) X is paramagnetic and Y is diamagnetic

B) X is ferromagnetic and Y is paramagnetic

C) X is diamagnetic and Y is ferromagnetic

D) X is diamagnetic and Y is paramagnetic