Code No: 09A1BS02 R09 Set No. 2
I B.Tech Regular Examinations,June 2010
ENGINEERING PHYSICS
1. (a) What is statistical mechanics? Write notes on Bose-Einstein statistics.
(b) Write notes on black body radiation.
(c) Calculate the energies that can be possessed by a particle of mass
8.50 _ 1031kg which is placed in an in_nite potential box of width 109cm.
[6+5+4]
2. (a) What is the meaning of nanotechnology? Explain.
(b) Describe the processes of \sol-gel" and \precipitation" in the fabrication of
nano- structures.
(c) Write the applications of nanotechnology in Electronic Industry. [4+7+4]
3. (a) Write notes on volume defects in crystals.
(b) What is Burger's vector? What is Burger's circuit? Explain.
(c) If the average energy required to create a Frenkel defect in an ionic crystal is
1.35 eV, calculate the ratio of Frenkel defects at 250C and 3500C. [5+6+4]
4. (a) Discuss the band theory of solids and explain the formation of bands and
concept of holes.
(b) What is e_ective mass of an electron? Derive an expression for the e_ective
mass of an electron. [9+6]
5. (a) Explain the formation and properties of an ionic crystal, with a suitable ex-
ample.
(b) Derive an expression for the cohesive energy of an ionic crystal. [7+8]
6. (a) What is Meissner e_ect? Explain, in detail.
(b) Distinguish a super-conductor and a normal metal, both maintained at same
temperature.
(c) Write notes on magnetic levitation. [5+5+5]
7. (a) Explain the characteristics of a laser beam.
(b) Describe the construction of He-Ne laser and discuss with relevant ELD, the
working of He-Ne laser.
(c) What are the di_erences between a laser diode and an LED? [4+7+4]
8. (a) Derive an expression for carrier concentration of p-type semiconductors.
(b) Explain Hall e_ect and its importance.
(c) For a semiconductor, the Hall coe_cient is -6.85 _ 105 m3/coulomb, and
electrical conductivity is 250 m11. Calculate the density and mobility of
the charge carriers. [7+4+4]
Code No: 09A1BS02 R09 Set No. 4
1. (a) Obtain an expression for Fermi energy at T > 0 K.
(b) Derive an expression for density of states of electrons.
(c) Write short notes on:
i. De Broglie wavelength and
ii. Heisenberg's uncertainty principle. [4+7+4]
2. (a) Derive Bragg's law of crystal di_raction.
(b) Describe, in detail, Debye-Scherrer method for the determination of crystal
parameter.
(c) A certain crystal reects monochromatic X-rays strongly when Bragg's angle
is 210 for the second order di_raction. Calculate the glancing angle for third
order spectrum. [4+7+4]
3. (a) What is bonding in solids? Write the list of di_erent types of bonding in
solids.
(b) Describe with suitable examples, the formation of covalent and Vander-Waal's
bonds in solids.
(c) What is bonding energy of a molecule? Explain. [4+7+4]
4. (a) Describe the top-down methods by which nanomaterials are fabricated.
(b) Explain how X-ray di_raction can be used to characterize nanoparticles.[9+6]
5. (a) Discuss the propagation mechanism of light waves in optical _bers.
(b) Derive the expression for the numerical aperture of an optical _ber.
(c) A step index _ber has a numerical aperture of 0.16, and core refractive index
of 1.45. Calculate the acceptance angle of the _ber and the refractive index
of the cladding. [5+6+4]
6. (a) Using Kronig-Penney model show that the energy spectrum of an electron
contains a number of allowed energy bands separated by forbidden bands.
(b) De_ne e_ective mass of an electron. Explain its physical signi_cance. [9+6]
7. (a) Show that the application of forward bias voltage across p-n junction causes
an exponential increase in number of charge carriers in opposite regions.
(b) Write notes on \Liquid Crystal Display".
(c) The current in a p-n junction at 270C, is 0.18 _A when a large reverse bias
voltage is applied. Calculate the current when a forward bias of 0.98 V is
applied. [7+4+4]
8. (a) De_ne the terms magnetic induction (B), magnetization (M) and magnetic
_eld (H). Obtain an expression relating to these quantities.
(b) What are ferrites? Prove that ferrites are superior to ferro-magnetic materils.
Write the applications of ferrites.
(c) The magnetic susceptibility of aluminum is 2.3 _ 105. Find its permeability
and relative permeability. [6+5+4]
Code No: 09A1BS02 R09 Set No. 1
1. (a) Explain the principle behind the functioning of an optical _bre.
(b) Derive an expression for numerical aperture of an optical _bre.
(c) Write any three applications of optical _bres. [4+7+4]
2. (a) Distinguish between intrinsic and extrinsic semicondutors.
(b) Derive an expression for the density of holes in the valence band of an intrinsic
semiconductor. [7+8]
3. (a) What is bonding in solids? Write the list of di_erent types of bonding in
solids.
(b) Describe with suitable examples, the formation of ionic and covalent bonds in
solids.
(c) What is cohesive energy of a molecule? Explain. [4+7+4]
4. (a) What is Bloch theorem? Explain.
(b) Write the conclusions given by Kronig-Penney model.
(c) For an electron under motion in a periodic potential, plot the curve between
the e_ective mass of the electron and wave number, and explain. [5+5+5]
5. (a) Describe any three processes by which nanomaterials are fabricated.
(b) Describe the important applications of nanotechnology. [9+6]
6. (a) De_ne magnetic moment. What is Bohr magneton? Explain.
(b) What are the characteristics of diamagnetic, paramagnetic and ferromagnetic
substances? Explain their behavior with the help of examples.
(c) If a magnetic _eld of strength 300 amp/metre produces a magnetization of
4200 A/m in a ferromagnetic material, _nd the relative permeability of the
material. [3+9+3]
7. (a) Explain the concept of dual nature of the light.
(b) Describe the experimental veri_cation of matter waves using Davisson-Germer
experiment.
(c) Calculate the wavelength of matter wave associated with a neutron whose
kinetic energy is 1.5 times the rest mass of electron.
(Given that Mass of neutron = 1.676 _ 1027 kg, Mass of electron = 9.1 _ 1031 kg, Planck's constant = 6.62 _ 1034 J-sec, Velocity of light = 3 _ 108
m/s). [4+7+4]
8. (a) Write notes on Bragg's law.
(b) Describe Bragg's X-ray spectrometer method in the determination crystal
structure.
(c) Calculate the glancing angle of (1 1 1) plane of a cubic crystal having axial
length 0.19 nm corresponding to the second order di_raction maximum for
the X-rays of wavelength 0.058 nm. [4+7+4]
Code No: 09A1BS02 R09 Set No. 3
1. (a) Explain Fermi-Dirac distribution function. Illustrate the e_ect of temperature
on the distribution.
(b) Derive an expression for density of states of an atom. [8+7]
2. (a) Derive the expressions for:
i. Acceptance angle and
ii. Numerical aperture of an optical _ber.
(b) Describe the di_erent types of _bers by giving the refractive index pro_les and
propagation details. [8+7]
3. (a) What are Brillouin zones? Explain using E-K diagram.
(b) De_ne e_ective mass of an electron. Explain its physical signi_cance.
(c) What is a hole? List out the properties of a hole. [5+5+5]
4. (a) Write notes on `point defects' in crystals..
(b) Derive the expression for the density of Frenkel defects in a metallic crystal.
(c) What is Burgers vector? Explain. [5+5+5]
5. (a) Describe the di_erent methods of acoustic quieting.
(b) Describe various method to achieve soundproo_ng. [7+8]
6. (a) Explain the terms:
i. Magnetic induction,
ii. Magnetic susceptibility,
iii. Permeability of a medium and
iv. Intensity of magnetization.
(b) What are hard and soft magnetic materials? Give their characteristic proper-
ties and applications.
(c) A paramagnetic material has a magnetic _eld intensity of 104 amp/m. If the
susceptibility of the material at room temperature is 3.7 _ 103. Calculate
the magnetization and ux density of the material. [6+5+4]
7. (a) What do you understand by Miller indices of a crystal plane?
(b) Show that in a cubic crystal the spacing (d) between consecutive parallel
planes of Miller indices (h k l) is given by d = a (h2 + k2 + l2)1=2.
(c) NaCl crystals have FCC structure. The density of NaCl is 2.18 gm/cm2.
Calculate the distance between two adjacent atoms. (Molecular weight of
NaCl = 58.5). [4+7+4]
8. (a) Derive an expression for density of electrons in intrinsic semiconductors.
(b) Explain the variation of Fermi level with temperature in the case of p-type
semiconductors.
(c) If the e_ective mass of holes in a semiconductor is 5 times that of electrons, at
what temperature would the Fermi level be shifted by 15% from the middle of
the forbidden energy gap? [Given that the energy gap for the semiconductor
is 1.20 eV]. [7+4+4]
