VTU First Year Engineering (P Cycle) (Semester 2)
Engineering Physics
December 2013
Total marks: --
Total time: --
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

Choose the correct answer for the following :-
1 (a) (i) De Broglie wavelength of an electron accelerated through a potential of 60 V is,
(A) 1.850 ?
(B) 1.584 ?
(C) 1.589 ?
(D) 1.570 ?
1 M
1 (a) (ii) The wavelength of maximum intensity is inversely proportional to the absolute temperature of the body emitting radiation. This is called,
(A) Stefan's law
(B) Wein's displacement law
(C) Rayleigh-jean's law
(D) Plank's law
1 M
1 (a) (iii) Einstein's photoelectric equation is given by,
(A) E=?+(KE)max
(B) E=?-(KE)max
(C) ?=E+(KE)max
(D) (KE)max=E+?
1 M
1 (a) (iv) Which of the following relations can be used to determine de Broglie wavelength associated with a particle?
\[ (A) \ \dfrac {h}{\sqrt{2mE}}\\(B) \ \dfrac {h}{mV}\\(C) \ \dfrac {h}{\sqrt{2meV}}\\(D) \ all \ of \ these \\\]
1 M
1 (b) Explain Wein's law and Rayleigh-Jean's law. Mention their drawbacks,
6 M
1 (c) Define phase velocity and group velocity. Derive a relation between the two.
6 M
1 (d) Calculate the wavelenght associated with electrons whose sped is 0.01 part of the speed of light.
4 M

Choose that correct answer for the following :-
2 (a) (i) For a particle in an infinite potential well in its 1st excited state, the probability of finding the particle at the center of box is,
(A) 0
(B) 0.25
(C) 0.5
(D) 0.1
1 M
2 (a) (ii) The Heisenberg's Uncertainty relation for position of a particle is given by,
\[ (A) \ \Delta P, \Delta x \ge \dfrac {h}{2}\\(B) \ \Delta P, \Delta x \le \dfrac {h}{4\pi}\\(C) \ \Delta P, \Delta x \ge \dfrac {h}{4\pi}\\(D) \ \Delta P, \Delta x \ge \dfrac {h}{\pi}\\\]
1 M
2 (a) (iii) According to Max Born approximation |?|2 represents,
(A) particle density
(B) Charge density
(C) Energy density
(D) Probability density
1 M
2 (a) (iv) Schrodinger's time independent wave equation is applicable for the particle with,
(A) Constant energy
(B) Variable energy
(C) Only constant potensital energy
(D) All of these
1 M
2 (b) Set up time independent Schrodinger wave equation.
6 M
2 (c) Explain Heisenberg's Uncertanity principle. Give its physical significance.
6 M
2 (d) An electron is bound in one dimensional infinite well fo width 0.12 mm. find the energy value and de Broglie wave length in the first excited state.
4 M

Choose the correct answer for the following :-
3 (a) (i) The motor specific heat of a gas constant volume is given by,
\[ (A) \ C_V=\dfrac {2R}{3} \\(B) \ C_V=\dfrac {3R}{2} \\(C) \ C_V=\dfrac {4R}{3} \\(D) \ C_{V}\dfrac {3R}{4}\\\]
1 M
3 (a) (ii) IF the Fermi energy of silver is 5.5 eV, the Fermi velocity of conduction electron is,
(A) 0.98×106 m/S
(B) 1.39×106 m/S
(C) 2.46×105 m/S
(D) None of these
1 M
3 (a) (iii) Matthiessen's rule is given by,
\[ (A) \ \rho=\rho_{ph}-\rho_{i}\\(B) \ \rho=\dfrac {\rho_{ph}}{\rho_{i}}\\(C) \ \rho=\rho_{ph}+\rho\\(D) \ \rho=\dfrac {\rho_{i}}{\rho_{ph}}\\\]
1 M
3 (a) (iv) The value of Fermi distribution function at ? =0 K is 1, under the condition,
(A) E=Er
(B) E>Er
(C) E>>Er
(D) Er
1 M
3 (b) Explain failure of classical free electron theory.
6 M
3 (c) Explain the probability of occupation of various energy states by electron at T=0 K and T>0 K on the basis of Fermi factor.
6 M
3 (d) Find the temperature at which there is 1.0% probability that a state with an energy 0.5 eV above Fermi energy wiil be occupied.
4 M

Choose the correct answer for the following :-
4 (a) (i) Choose the correct relation,
(A) E=?0(?r-1)P
(B) P=?0(?r-1)E
(C) ?r=K-1
(D) D=?0(?r-1)E
1 M
4 (a) (ii) For ferromagnetic substance, the Curie-Weiss law is given by,
\[(A) \ X=\dfrac {C}{T}\\ (B) \ X=\dfrac {C}{(T-\theta)}\\(C) \ X=\dfrac {(T-\theta)}{C}\\(D) \ X=\dfrac {C}{(T+\theta)}\\\]
1 M
4 (a) (iii) The only polarization mechanism at frequencies exceeding 1013 Hz is,
(A) ionic
(B) electronic
(C) orientation
(D) space charge
1 M
4 (a) (iv) Sulphur is an elemental solid dielectric of atomic weight 32.07 and density 2.07×103 kgm-3. The number of atoms per unit volume for Sulphur is,
(A) 3.89×1028/m3
(B) 3.89×1025/m3
(C) 9.3×1024/m3
(D) None of these
1 M
4 (b) Derive an expression for internal field in case of one dimensional array of atoms in dielectric solid.
8 M
4 (c) Describe ferroelectrics.
4 M
4 (d) If a WaCI 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 constanr of NaCl.
4 M

Choose the correct answer for the following :-
5 (a) (i) If n1 is the number density of lower energy E1 and n2 is the number density of higher energy E2 then n2 > n1 is called,
(A) thick population
(B) Inverted population
(C) normal population
(D) no population
1 M
5 (a) (ii) The number of modes of standing waves in the resonant cavity of length 1 m, if He-We laser operating at wavelength of 6328 ? is
(A) 3.16×106
(B) 1.58×106
(C) 3.16×108
(D) None of these
1 M
5 (a) (iii) Image is stored on a hologram in the form of
(A) interference pattern
(B) diffraction pattern
(C) photograph
(D) none of these
1 M
5 (a) (iv) The realation between Einstein's coefficients A & B is
\[ (A) \ \dfrac {8\pi h \lambda^3}{C^3}\\(B) \ \dfrac {8\pi h^2r^3}{C^3}\\(C) \ \dfrac {8\pi hr^3}{C^3}\\(D) \ \dfrac {8 \pi hr^{3}}{C^3}\\\]
1 M
5 (b) Explain the process of spontaneous and stimulated emission.
6 M
5 (c) Describe the construction and working of semiconductor laser.
6 M
5 (d) A pulse laser has an average power output 1.5 mW per pulse and pulse duration is 20 ns. The number of photon emitted per pulse is estimated to be 1.047×108. Find the wavelength of the emitted laser.
4 M

Choose the correct answer for the following :-
6 (a) (i) The variation of critical field Hc with temperature T is given by,
\[(A) \ H_C=H_O\left [ 1- \left ( \dfrac {T}{T_{C}}\right )^2 \right ]\\(B) \ H_C=H_O\left [1+ \left (\dfrac {T}{T_C} \right )^2 \right ]\\(C) \ H_C=H_O\left [1- \dfrac {T}{T_C} \right ]\\(D) \ H_C=H_O \left [ 1+ \dfrac {T}{T_C} \right ]\]
1 M
6 (a) (ii) The quantum of magnetic flux is given by,
\[ (A) \ \dfrac {2e}{h}\\(B) \ \dfrac {h}{2e}\\(C) \ \dfrac {he}{2} \\(D) \ \dfrac {2\pi h}{e}\\\]
1 M
6 (a) (iii) Fractional index change of optical fibre and reflective index of core are 0.00515 and 1.533 repsectively. The cladding refractive index is,
(A) 1.492
(B) 1.525
(C) 1.499
(D) 1.511
1 M
6 (a) (iv) The attenuation of a fibre-optical cable is expressed in,
(A) ohm/km
(B) watt/km
(C) decibel/km
(D) joule/km
1 M
6 (b) Describe type-I and type-II superconductors.
6 M
6 (c) What is attenuation? Explain any two factors contributing to the fibre loss.
6 M
6 (d) The angle of acceptance of an optical fibre is 30o when kept in air. Find the angle of acceptance when it is in a medium of refractive index 1.33
4 M

Choose the correct answer for the following :-
7 (a) (i) The relation between atomic radius and lattice constant a in FCC structure is
\[(A)\ a=2R \\ (B) \ a=2\sqrt{2} R \\ (C) \ a= \dfrac{\sqrt{3}}{4} R \\ (D)\ a=\dfrac{4}{\sqrt{3}}R \]
1 M
7 (a) (ii) The crystal with lattices a = b ? c and angles ? = ? = ? = 90o represents,
(A) cubic
(B) hexagonal
(C) orthorhombic
(D) tetragonal
1 M
7 (a) (iii) The number of atoms per present in the unit cell of diamond cubic crystal structure is,
(A) 2
(B) 4
(C) 8
(D) 16
1 M
7 (a) (iv) Bragg's law is given by,
\[(A)\ 2 \sin \theta = n\lambda \\(B)\ 2d \sin \theta = n\lambda \\(C)\ \dfrac{2dn}{\sin \theta}=\lambda \\ (D)\ 2n\lambda = sin \theta \]
1 M
7 (b) Define (i) Coordination number
(B) Packing factor, calculate the atomic packing factor fo BCC structure.
6 M
7 (c) Sketch the (1 1 2) , (1 1 0) and (1 0 0) planes in a simple cubic unit. Explain the procedure for obtaining miller indices.
6 M
7 (d) The minimum order of Bragg's reflection occurs at an angle of 20o in the plane (2 1 2). Find the wavelenght of X-rays if lattice constant is 3.615 ?
4 M

Choose the correct answer for the following :-
8 (a) (i) In a carbon nanotube the bond between the carbon atom is,
(A) metalic
(B) ionic
(C) hydrogen
(D) covalent
1 M
8 (a) (ii) A constant testing of product causing any damage is called,
(A) minute testing
(B) destructive testing
(C) non-destructive testing
(D) random testing
1 M
8 (a) (iii) Ultrasonic waves are sound waves having,
(A) Velocity greater than 330 mS-1
(B) Velocity less than 330 mS-1
(C) Frequency greater than 20 kHz
(D) Frequency less than 20 kHz
1 M
8 (a) (iv) Which of the procedure is not employed to detect the internal flows by a material,
(A) Ultrasonic method
(B) Magnetic method
(C) Alpha ray method
(D) Dynamic testing
1 M
8 (b) Explain carbon nanotubes and its application by giving physical properties.
8 M
8 (c) What are ultrasonic? Explain with a diagram a method for measurement of velocity of ultrasonic waves in liquids.
8 M

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