West Bengal Institute of Technology (WBIT) 2009 B.Tech Computer Science and Engineering Engineering physics - Question Paper
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CS / iJ .TE CH(0+N) / SEM-2 / i*jl*201/09 3
ENGINEERING & MANAGEMENT EXAMINATION, JUNE - 2009
ENGINEERING PHYSICS >JMESTER - 2
Time ; 3 Hours ] [ Full Marks : 70
GROUP - A ( Multipit Choice Type Questions ;
1. Choose the correct alternatives for any ten of the following ; 10x1 = 10
i) Newton's dug experiment is based on
a) division of amplitude
b) division of wave-front . ,
c) none of these
ti) de Broglie wavelength of a particle of mass m and kinetic energy E is
b) h
"u
\ V2m& c> h
iii) Mass of a photon of frequencies v is given by hv
HI JlV
W JTS
. hv2 c) __
iv) The eigenvunu; of the eigenfunction e u for the operator is
a) l ' ,
>) 0
c) - 1.
jJ,/t.TECIiiC'ri;)/SEIv;-2/i;H-20X/CS 4
v) Miller indices of a plane which cut intercepts of 2. 3 and 4 units along the thi\
axes are
( 2, 3, 2
aj
b) ( 2, 3, 4 )
c) (6,4,3). .
lu a plane transmission grating, light aj /'diffracts to produce the resultant pattern
vl)
b) diffracts and interfares to produce the resultant pattern
c) interfares to produce the resultant pattern.
vii) The atomic radius of a face centred cubic crystal of lattice constant a is
u
a)
b)
c]
V3a
4
V_2a
~4
An X-ray tube is subjected to a potential difference of 50 kV with the corresponding current of 8 mA through it. The number of electrons striking p.. r second on the target material is
viii)
a) 5 x 1013
b) 6 x 1011
e) none of these. ' CZ_____1
In l ie Ne laser, the laser light emits due to the transition from
ix)
a) 3 s 2p
b) 3s - 3p
c) 2s 2p. C__2
For an optical fibre, if n0, n1 and n2 are the refractive index of air, core and cladding region respectively, then
x)
a) n0 > ri2 > n1 .
b) nj > na > rio
c) n2 > nj > Hq . !____I
xi) If the speed of an electron increases, the specific cheirge
5
co/b.vKCiHo+Nj/sEw-a/wa-aoi/os
a) increases
b) decreases
c) remains constant. ___J
xii) One milligram of matter converted Into energy will give
a) 90 joule ,
b) 9 x iO10 joule
c) None-'of these. ' __
f;
xlii) Relative velocity of two particles moving with velocity (C) of light in opposite
direction is
a) C
b)
c) O.
GROUP -B ( Short Answer Type Questions }
Answer any three of the following,
3x5=15
2, a) What is the difference between temporal coherence and spatial coherence ? 2
bj if the amplitudes of two coherent light waves are in the ratio 1 ; 4, find the ratio of maximum and minimum intensity in the interference pattern, 3
3. a) What is Compton effect ? Calculate the Compton wavelength for an electron.
b) Why does the unmodified line appear in Compton scattering ?
2
1
4. a) Deduce the formulae for interplaner spacing of a simple cubic crystal, b) Why X-ray diffraction is used for crystal structure analysis ?
5. Kind the possible arrangements of two particles in three cells for
i) Bose-Einsvein Statistics &
ermi-Dirac Statistics.
',5%air
a) Describe briefly the working principle of laser action. 3
b) Mention at least three main advantages of optical fibre over wire or cable ? 2
a) What, are the basic postulates of special theory of relativity ? 2
b) Show that for V' C, Lorentz transformation reduces to the Galilean transformation. 3
a) Discuss the important characteristics of nuclear forces. 2
b) Why nuclear fission reaction must be done first before nuclear fusion ? 3
GROUP -C ( Long Answer Type Questions )
Answer any three questions. 3xi5 = 4i
9. a) What is double refracting crystal ? i
b) Discuss Nicol prism as polarizer and analyzer. /:
c) Determine the Brewsters angle for glass of refractive index 15, immersed ir,, water of refractive index 1-33. C
d) Prove that the intensit of secondary maxima formed for Fraunhofer diffraction. ai
a single slit are of decreasing order. j
e) in :i plane transmission grating the angle of diffraction for 2nd order maxima for. wavelength 5 x 10 ~5 cm is 30. Calculate the number of lines in one centimetre ef the grating surface. 3
10. a) State and explain de Broglie hypothesis. >
b) Prove that the product of phase velocity and group velocity for a de Brogiie v av i: is equal to the square of the velocity of light. , 5
c) Compute the smallest possible uncertainty in the position of an electron mt in * with velocity 3 x 10 7 m/s. The rest mass of electron is 91 x 10 ~31 kg. 3
d) Derive the Weins displacement law from Planck's radiation law. 5
11. a) Write down the.postulates of Fermi-Dirac statistics. 3
b) Plot electron distribution function governed by Fermi-Dirac statistics in me; 1 at i = OK and T > OK. Explain their physical significance. 2 + ( 3 c )
c) Way Compton effect can not be observed with visible light but can be obs. ;Ved due to X-rays ? 4
,2. a) Discuss the operation of a Ruby laser with the help of energy level diagram. 5 + i
b) Find the numerical aperture and angle of acceptance of a given optical fibre.
I Given, the refractive Indices of core and cladding are 1-562 and 1497
respectively ].
3
c) In a He-Ne laser transition from 3s to 2p level gives a laser beam of wavelength 632 8 nm. If the 2p level has energy equal to 15-2 x 10 ~19 J, calculate the required pumping energy ( assuming no loss of energy ). 4
d) What is the role of optical resonator in laser production ? 2
a) Write down Schrodinger equation for one dimensional motion of a free particle in i one dimensional potential box. Find its eigenfunction and eigenenergy.
b) Prove that the first excited energy state of a free particle in a cubical box ha.': three fold degeneracy. 1
c) Copper has FCC structure and the atomic radius is 0 1278 nm. Find its density . and the interplaner spacing for ( 321 ) planes. The atomic weight of copper i
33-5. : 4
14. a) What are the differences between inertial and non-inertial frame of references ?
b) Deduce an expression of time dilation on the basis of Lorentz transformation
equation.
c) Find the mass and speed of 2 MeV electron.
dj If the total energy of a particle is thrice of its rtst energy, find the velocity of th : particie. ,_j
5. a) What is nuclear binding eaergy ? 2
b) Draw a binding energy cur/e. What informations do you set from such a carve ?
c) Find the energy released for the following nuclear iussion reaction :
4 I H 1 -* 2 he 4 + 2 +1 e + energy '
Given that
mass of j H 1 atom = 1 007825 amu mass of 2 He 4 atom = 4-0026 amu mass of ,, e ( positron ) - 0-00055 amu,
d; Differentiate conductor, insulator and semiconductor on the basis of energy band diagram. 3
END
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