USN
10PHY12/22

First/Second
Semester B.E. Degree Examination, June 2014

**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 = 3×10^{8}m/s, m_{e}= 9.1×10^{-31}kg,
k = 1.38×10

^{-23}J/K, ε_{0}= 8.854×10^{-12}F/m**PART-A**

**1**a. i) The law which describes the blackbody radiation completely is

A) Planck’s law

_{ }B) Stefan’s law C) Wien’s law D) Rayleigh-Jean’s law_{ }
ii) Photoelectric
effect establishes

A) wave nature of light
B) particle nature of light C) dual nature of light D)
None of these

_{ }
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) If the group
velocity of the de-Broglie waves associated with a particle is 3×10

^{4}m/sec, the velocity of the particle is
A) 3×10

^{8}m/s B) 3×10^{12}m/s C) 3×10^{4}m/s D) None of these
b. Describe Davisson and
Germer experiment for confirmation of de-Broglie hypothesis.
(06marks)

c. What is Planck’s radiation law?
Show how Wien’s law and Rayleigh-Jean’s law can be
derived from it. (06 Marks)

d

**.**Find the de-Broglie wavelength of particle of mass 0.65 MeV/C^{2 }has a kinetic energy 80 eV. (04 marks)**2**a. i) The probability of finding the particle within an element of volume dτ is

- 0 B) ∫│ψ
^{2}│dτ C) ∫│ψ│dτ D) ∫│ψ^{*}│dτ

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) For a particle which is not
bound to any system and is free, the energy eigen value is,

A) zero B) finite but not
quantized C) infinity D) finite but quantized

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. State and explain
Heisenberg’s uncertainty principle and prove that nuclei do not
contain electron. (05 Marks)

d.
A quantum particle confined to one dimensional box of width ‘a’
is in its first excited state. What is the probability of finding the
particle over an interval of ( marked symmetrically at the centre of
box.
(05 Marks)

**3**a. i) The fermi factor for E = E

_{F}at T > 0K is

A) 1 B) ½ C)
0 D) 2

ii) Mobility of
electron is

A) Reciprocal of
conductivity B) Flow of electrons per unit

C) Reciprocal of
resistivity D) Average electron drift velocity per unit electric
field

iii) According to
quantum free electron theory, the energy level in a metal are

A) Continuous
B) Discrete C) Overlapping D) None

iv) For ordinary
metals, resistivity versus temperature curve at T = 0K

A) has a positive
intercept B) has a negative intercept

C) goes through the
origin D) none of these (04 Marks)

**b.**Using the free electron theory, derive an expression for electrical conductivity in metals.

**(06 Marks)**

c. Discuss the various
drawbacks of classical free electron theory of metals. What are the
assuptions made in Quantum theory to overcome the same? (06 Marks)

d. Calculate the
probability of an electron occupying an energy level 0.02 eV above
the Fermi level and 0.02 eV below the Fermi level at 200 K. (04
marks)

**4**a. i) Electronic polarisation

A) Independent of
temperature B) Increases with temperature

C) Decreases with
temperature D) None of these

ii) Which of the
following is a piezoelectric material?

A) lead B) mica C)
iron D) quartz

iii) Above Curie
temperature, ferromagnetic substance becomes

A) antiferromagnetic B)
strongly ferromagnetic C) paramagnetic D) diamagnetic

iv) If two charges q
are separated by a distance L, dipole moment of the system is

A) q/L B) L/q C) qL D)
q/L

^{2}(04 Marks)
b. Derive the expression
for internal field in solids. (06 Marks)

c. Derive
Claussius-Mossoti equation. (06 Marks)

d. Sulphur is elemental
solid dielectric whose dielectric constant is 3.4. Calculate
electronic polarizability if its density is 2.07× 10

^{3}kg/m^{3}and atomic weight is 32.07. (04 Marks)**PART-B**

**5**a. The pumping action in diode laser is by,

- Optical pumping B) Electric discharge C) Reverse bias D) Forward bias

ii) The life time of
an atom in a metastable state is of the order of

- A few seconds B) unlimited time C) a nanosecond D) few milliseconds

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) The required
condition to achieve laser action in a system is

A) state of
population inversion B) existence of metastable
state

C) a resonant
cavity D) all the three

b. What is holography? Explain
principle of hologram recording using laser. (05Marks)

c. Explain the
construction and working of He-Ne laser, with the help of suitable
diagrams.

(07 Marks)

d. The average output
power of laser source emitting a laser beam of wavelength 633nm is 5
mW. Find the number of photons emitted per second by the laser
source. (04 Marks)

**6**a. i) According to Meissner effect, material in superconducting state is,

A) Paramagnetic B)diamagnetic C)
ferromagnetic D) anti-ferromagnetic

ii) Attenuation in optic fiber is
due to

A) absorption B) scattering
C) radiation loss D) all the above

iii) The conductivity of a
superconductor is

A) infinite B) Zero C) finite
D) none of these

iv)

**In a single mode fiber, the diameter of the core is nearly equal to**
A) 125 m
B) 100 m C) 50 m D) 10 m

**(**04 Marks)
b. Discuss BCS theory of
superconductor. Explain SQUID. (07 Marks)

c. Describe the point to
point communication system, with the help of block diagram (05 Marks)

d.

**The refractive indices of core and cladding are 1.50 and 1.48 respectively in an optical fiber. Find the numerical aperture and angle of acceptance.****(04 Marks)****7**a. i) Packing factor of diamond crystal is

- 34% B) 52% C) 68% D) 74%

ii) In Bragg’s
spectrometer, for every rotation θ of the
turn table, the detector turns by an angle,

A)θ
B) 4θ C) 2θ D)
θ/2

iii) The miller
indices of the plane parallel to the x and y axes are

A) (100) B) (010) C)
(001) D) (111)

iv

**)**Which one of the following Bravais lattices is not found in cubic crystal?
A) Simple cubic B) Face
centered C) Body centered D) Base centered (04 Marks)

b. Derive expression for
interplanar spacing in terms of Miller indices (06 Marks)

c. Explain how Bragg’s
spectrometer is used for determination of interplanar spacing in a
crystal. (04Marks)

d. Calculate the glancing
angle of the (110) plane of a simple cubic crystal (a=2.814Å)
corresponding to second order diffraction maximum for the x-rays of
wavelength 0.710 Å. (04 Marks)

8 a. i) The minimum size
of the matter below which the properties become size dependent is
called

A) Pico size B) Nano
size C) Micro size D) Macro size

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) The elastic
behavior of a liquid is characterized by its

A) Youngs modulus B)
Modulus of rigidity C) Bulk modulus D) Poisson’s ratio

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. (06 Marks)

c. What is NDT? Describe
the NDT method of detection of flaws in solid using ultrasound.
(06Marks)

d. Explain two methods of
preparation of Nanomaterials in brief. (04 Marks)