USN 10PHY12/22
First/Second Semester B.E. Degree Examination, June
2013
Engineering Physics
Time: 3 hrs. Max.
Marks:100
Note: 1. Answer any FIVE full
questions, choosing atleast two from each part.
2. Answer all objective type
questions only in OMR sheet page 5 of the answer booklet.
3. Answer to objective type questions
on sheets other than OMR will not be valued.
4. Physical constants: h = 6.626×10-34
Js, c = 3×108 m/s, me = 9.1×10-31 kg,
k
= 1.38×10-23 J/K, ε0 = 8.854×10-12 F/m
PART-A
1 a. i) Ke,Kp
and Ka are
respective energy of an e-, a proton and aparticle of
same de-Broglie wavelength. Then,
A) Ke>Kp>Ka B) Ke>Kpa C) Kep
ii) Recoil electron in Compton scattering carry maximum kinetic energy
when x-ray scattering angle θ =
A) 1800 B) 00 C) 900 D) 650
ii) Experimental evidence for the
existence of matter waves was first provided by
A) de-Broglie B) Davisson and Germer
C) G.P.Thomson D)
Max Planck
iv) Green light incident on a surface
releases photoelectrons from the surface. If now blue light is incident on the
same surface, the velocity of electrons
A) increases B) decreases C) remains same D) becomes zero (04 marks)
b. Show that group velocity is equal to particle velocity. (05marks)
c. What is Planck’s
radiation law? Show how Wien’s law and
Rayleigh-Jean’s law can be
derived from it. (07 Marks)
d.
An electron beam has a de-Broglie wavelength of 2 ×10-12 m. Find the
kinetic energy, phase and group velocities of de-Broglie waves. (04 marks)
2 a. i) If free electron exists in a nucleus, its energy value must
have a minimum energy of about
A) 4 MeV B) 9.9 MeV C) 9.9 KeV D) 4 KeV
ii) The product of uncertainty between
angular momentum and angular displacement is
A) ≥ ħ/2p B) ≥ ħ /4p C) ≤ ħ /4p
D) ≥ ħ /2
iii) If E1 is the energy of the
lowest state of a one dimensional potential box of length ‘a’ and E2
is the energy of the lowest state when the length of the box is halved, then
A) E2 = E1 B) E2 = 2E2
C) E2 = E1/2 D) E2 = 4E1
iv) The wavefunction is acceptable if it is
A) Finite everywhere B) Continuous everywhere
C) Single valued everywhere D) All of
these
(04
Marks)
b. Solve the Schrödinger’s wave equation for
allowed energy values in case of a particle in a potential box. (06
Marks)
c. What is a wave function?
Explain the properties of a wave function. (04 Marks)
d. An electron is bound in one
dimensional potential well of width 0.18 nm. Find the energy value in eV of the
second excited state. (04
Marks)
3 a. i) The
classical value of molar specific heat of a conductor is
A) 3/2 R B) ½ R C) 3R D)
5/2 R
ii) The Fermi energy of a metal at
absolute zero temperature is proportional to
A) n1/3 B) n3/2 C) n2/3 D) n2
iii) According to quantum free electron
theory, the energy level in a metal are
A) Continuous B)
Discrete C) Overlapping D) None
iv) Which one of the following is
correct for current density?
A) J = neAvd B) J = neA/vd C) J = nevd D) J = 1/nevd
(04
Marks)
b. Define relaxation time and
discuss the dependence of electrical resistivity of metals with temperature and
impurity. (06
Marks)
c. What is Fermi energy? Discuss
variation of Fermi factor with energy and temperature. (06 marks)
d. A uniform silver wire has
resistivity 1.54×10-8 ohm-m at room temperature for an electric
field 2 v/m. Calculate relaxation time
and drift velocity of the electrons, assuming that there are 5.8×1022
conduction electrons per cm3 of the material. (04
marks)
4 a. i) Orientation polarization occurs
A) In all dielectrics B) in polar dielectrics C) in non-polar dielectrics
D) in ionic dielectrics
ii) Ultrasonic waves can be produced by
A) Photoelectric effect method
B) Inverse piezoelectric effect method
C) Dielectric heating method D) High energy ball milling
method
iii) The susceptibility of a diamagnetic material is
A) Infinity B) positive C) zero D)
negative
iv) In a magnetic material, the major contributor to magnetism is
A) orbital motion of electrons B) nuclear spin
C) spin motion of electrons D) none of these (04
Marks)
b. Derive the expression for
internal field in solids. (08
Marks)
c. What are soft magnetic
materials? Discuss their properties. (04 Marks)
d. If NaCl crystal is subjected
to an electric field of 1000 V/m and the resulting polarization is 4.3×10-8
c/m2, calculate the static dielectric constant of NaCl. (04 Marks)
PART-B
5 a. i) In
semiconductor laser, the material used is
A) any semiconductor B) direct band gap
semiconductor
C) indirect band gap
semiconductor D) not a semiconductor
ii) The number of modes of standing waves
in the resonant cavity of length 1m, if He-Ne laser operating at wavelength
6328 Å is
A) 3.16 × 106 B) 3.16 × 1010 C) 3.16 × 108 D) None of these
iii) Emission of a photon by an excited atom due to interaction of
external energy is called
A) Spontaneous emission B) Stimulated emission C) Induced absorption
D) Light amplification
iv) 3D image of an
object constructed by hologram is the process of
A) Intensity recording B) Phase
information recording
C) Both phase and intensity
information recording (04 Marks)
b. Write a note on measurement of
pollutants in atmosphere using laser. (06Marks)
c. Explain the construction and
working of He-Ne laser, with the help of suitable diagrams.
(05 Marks)
d. The ratio of population of two
energy levels is 1.059×10-30. Find the wavelength of light emitted
at 300K. (04 Marks)
6 a. i) Graded
index fiber can be
A) single mode fiber only
B) multimode fiber only
C) both single mode and multimode
D) depends on the surrounding medium
ii) The loss of
power by the optical signal through the optical fiber is mainly due to
A)
Rayleigh scattering
B) Raman scattering C) Wien’s
scattering
D) All of these
iii) When the
type-I superconducting material is placed in an external magnetic field, it
A) attracts the magnetic
lines B) enhances the magnetic flux
lines
C) repels the magnetic flux lines
D) does not influence magnetic
field of lines
iv) Superconductors
are
A)
Diamagnetic B) paramagnetic C) ferromagnetic D)
antiferromagnetic (04
Marks)
b. Discuss BCS theory of
superconductor. Explain SQUID. (07 Marks)
c. Derive the expression for
numerical aperture of an optical fiber. (05 Marks)
d. The angle of acceptance of an
optical fiber is 300 when kept in air. Find the angle of acceptance
when it is in a medium of refractive index 1.33. (04 Marks)
7 a. i) Four types of Bravais lattices are observed in
A) Rhomohedral system B) Orthorhombic system
C) Triclinic system D) Monoclinic system
ii) A plane intercepts at a, b/2, 2c in a
simple cubic unit cell. The miller indices of the plane are
A) (214) B) (241) C)
(421) D) (124)
iii) The coordination number for a face
centered cubic lattice is
A) 12 B)
8 C) 6 D) 26
iv) For every rotation by angle q in
Bragg’s spectrometer, detector turns by an angle
A) q B)3q C)
4q
D) 2q (04 Marks)
b. Define unit cell and primitive
cell. Describe crystal structure of diamond. (08
Marks)
c. Derive Bragg’s law for X-ray
diffraction. (04Marks)
d. Calculate the glancing angle
for incidence of X-rays of wavelength 0.58Å on the plane (132) of NaCl which
results in second order diffraction maxima taking the lattice as 3.81Å. (04
Marks)
8 a. i) In a carbon nanotube, the bond between the carbon atoms is
A) Metallic B) ionic C)
covalent D) hydrogen
ii) A constant testing of product without causing any damage is called
A) minute testing B) destructive testing C) non-destructive testing D) random testing
iii) Ultrasonic waves can exist only as longitudinal waves in
A) Solid B) Liquid C) Gases D) All the above
iv) The state of matter around the nanosize
is known as
A) Liquid state B) Plasma state
C) Mesoscopic state D) Solid state (04 Marks)
b. Explain density of states for
various quantum structures. (08 Marks)
c. Describe a method of measuring
velocity of ultrasonic waves in liquid. (08 Marks)
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