Download VTU B-Tech/B.E 2019 June-July 1st And 2nd Semester 2014 June-July 10PHY12 Engineering Physics Question Paper

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CHIKODI

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

Engineering Physics

Time: 3 hrs.

Max. Marks: 100

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Note: 1. Answer any FIVE full questions, choosing at least 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 : Velocity of light, c = 3 x 10⁸m/s

Planck's constant, h = 6.625x 10^-34J.S.

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Charge on electron, e =1.602 x 10^-19 C

Mass of electron, m = 9.1 x 10^-31 kg

Avagadro number, N_A = 6.02 x 10²⁶/k mole

Permittivity of vacuum, ε₀ = 8.85 x 10^-12 F/m

Boltzmann constant, k = 1.38 x 10 ^-23J/K.

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PART — A

1. a. Choose the correct answers for the following : (04 Marks)
   1. If an electron, proton, neutron and α - particle have the same velocity, the particle which has the largest wavelength is
      A) electron B) proton C) neutron D) α - particle
   2. The Compton shift for the back scattered photon is
      A) h/m₀c B) 2h/m₀c C) h/2m_ec D) 2h/3m₀c

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   3. The photoelectric effect is observed only if the wavelength of light is
      A) above threshold wavelength B) below threshold wavelength C) zero D) equal to threshold wavelength
   4. The law which failed to account for longer wavelength of blackbody radiation spectrum is
      A) Wein's law B) Rayleigh-Jean's law C) Plank's law D) Maxwell's law

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2. a. Choose the correct answers for the following : (04 Marks)
   1. From the Heisenberg's uncertainty relation, ΔL.ΔP ≥ h/4π L refers to
      A) length B) linear displacement C) angular displacement D) angular momentum
   2. The first excited state energy of a particle of mass m in a box of width 'a' is given by
      A) zero B) h²/8ma² C) 2h²/8ma² D) 4h²/8ma²
   3. Wave function associated with a material particle is
      

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      A) single valued B) finite C) continuous D) all of these
   4. If the uncertainty in momentum is large, the uncertainty in energy is
      A) small B) large C) zero D) independent

b. Describe photoelectric effect along with Einstein's explanation. (06 Marks)

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c. Describe Davisson and Germer experiment for confirmation of de-Broglie hypothesis. (07 Marks)

d. Calculate the kinetic energy of an electron of wavelength 18 nm [h = 6.63 x 10^-34] (03 Marks)

2. a. Choose the correct answers for the following : (04 Marks)
   1. The Fermi temperature is given by
      A) 2E_F/3K B) 3E_F/2K C) E_F/3K D) 2E_F/K
   2. If the mobility of an electron in a metal increases, the resistivity
      

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      A) decreases B) increases C) remains constant D) none of these
   3. The Fermi energy of a metal at absolute zero temperature is proportional to (n - number of free electrons per unit volume).
      A) n B) n^1/2 C) n^3/2 D) n²
   4. The electron energies in classical free electron theory follow
      A) Maxwell-Boltzmann statistics B) Fermi-Dirac statistics C) Bose-Einstein statistics D) none of these

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3. b. Obtain the time independent Schrodinger wave equation for a particle in one-dimensional potential well of infinite height and discuss the eigen values. (09 Marks)
4. c. What is Heisenberg's uncertainty principle? Discuss its significance. (03 Marks)
5. d. An excited atom has an average life time of 10^-8 seconds. During this period, it emits a photon and returns to the ground state. What is the minimum uncertainty in the frequency of this photon? (04 Marks)

b. Explain the failures of classical free electron theory. (06 Marks)

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c. Explain Fermi-energy and Fermi-factor. Discuss the probability of occupation of various energy states by electron at T=0°K and T > 0°K on the basis of Fermi factor. (06 Marks)

d. Calculate the mobility and relaxation time of electron in copper assuming that each atom contributes one free electron for conduction. Given resistivity of copper = 1.73 x 10^-8 ohm-m. At. weight = 63.5, density = 8.92 x 10³ kg/m³, N_A = 6.02 x 10²⁶/kg mole. (06 Marks)

4. a. Choose the correct answers for the following : (04 Marks)
   1. Copper is
      A) diamagnetic material B) paramagnetic material C) ferromagnetic material D) antiferromagnetic material
   2. Electronic polarization
      

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      A) increases with temperature B) decreases with temperature C) independent of temperature D) none of these
   3. The unit of dipole moment per unit volume is
      A) coulomb/metre B) coulomb/metre² C) coulomb/metre³ D) coulomb
   4. The electric susceptibility x =
      A) ε₀E/P B) E/ε₀P C) P/ε₀E D) ε₀P/E

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5. b. Describe the different polarization mechanism. (08 Marks)
6. c. Explain hysteresis of ferroelectrics. (05 Marks)
7. d. If a NaCl crystal is subjected to an electric field of 1 KV/m and the resulting polarization is 4.3 x 10^-8 c/m². Calculate the dielectric constant of NaCl [E₀ = 8.85 x 10^-12 F/m ]. (03 Marks)

PART – B

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5. a. Choose the correct answers for the following : (04 Marks)
   1. The life time of an atom on a metastable state is of the order
      A) a few seconds B) unlimited C) a nano second D) few millisecond
   2. The ratio of Einstein coefficients A/B is
      A) 8πhν³/c³ B) 8πhν³/c² C) 8πhν/c³ D) 8πhν²/c²
   3. Holography records
      

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      A) only amplitude B) only phase C) both amplitude and phase D) neither amplitude nor phase
   4. Pumping process in a diode laser is by
      A) optical pumping B) forward bias C) electric discharge D) none of these
6. b. Explain the construction and working of a He-Ne laser. (07 Marks)

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7. c. Explain the principle of holography and mention its applications. (05 Marks)
8. d. Find the ratio of populations of two energy levels in a laser if the transition between them produces light of wavelength 6493 Å, assuming the ambient temperature as 27°C. [K = 1.38 x 10^-23 J/K]. (04 Marks)

6. a. Choose the correct answers for the following : (04 Marks)
   1. If the angle of incidence of a ray is equal to the critical angle at the interface of core and cladding, then the ray travels
      A) in the cladding B) in the core C) along the interface D) in the buffer
   2. Fractional index change for the optical fibre of refractive index core and cladding 1.68 and 1.56 is
      

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      A) 0.0769 B) 0.0714 C) 1.0769 D) 0.9286
   3. A type II superconductor in the vortex state show
      A) complete Meissner effect and zero electrical resistivity
      B) incomplete Meissner effect and zero electrical resistivity
      C) complete Meissner effect and non-zero electrical resistivity
      

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      D) incomplete Meissner effect and non-zero electrical resistivity
   4. Below the critical temperature, if the temperature of superconductor is increased, the critical field
      A) increases B) deank C) remains constant D) independent
7. b. What is attenuation? Explain the various mechanisms through which attenuation takes place. (07 Marks)

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8. c. Explain type-I and type-II superconductors. (05 Marks)
9. d. The numerical aperture of an optical fibre is 0.2 when surrounded by air. Determine the RI of its core, given the RI of the cladding is 1.59. Also find the acceptance angle when the fibre is in water of RI 1.33. (04 Marks)

7. a. Choose the correct answers for the following : (04 Marks)
   1. A crystal of hexagonal lattice has unit cell with sides
      A) a?b?c, a?ß? 90° B) a = b = c, a =ß = ? = 90°
      C) a = b ? c, a =ß = 120°, ?=90° D) a = b ? c, a =ß = 90°, ? = 120°

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   2. A plane intercepts at a, 2b, 2c in a simple cubic unit cell. The miller indices of the plane are
      A) (214) B) (2 4 1) C) (4 2 1) D) (1 2 4)
   3. The coordination number in face centered cubic cell is
      A) 2 B) 6 C) 8 D) 12
   4. In the Bragg's equation, the angle ? is
      

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      A) the angle between the incident beam and the diffracted X-ray beam.
      B) the angle between the incident beam and the normal to the diffraction planes
      C) the angle between the incident beam and the diffraction planes
      D) none of these.

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8. b. Define packing factor. Calculate the packing factor for sc, bec and fcc structures. (07 Marks)
9. c. Describe the construction and working of a Bragg's X-ray spectrometer. (06 Marks)
10. d. Draw the following planes in a cubic unit cell: i) (2 0 0) ii) (210) iii) (1 3 2) (03 Marks)

8. a. Choose the correct answers for the following : (04 Marks)
   1. Carbon nanotubes are made up of
      A) graphene B) mica sheet layers C) honey comb D) plastic

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   2. The state of matter around the nano-size is known as
      A) solid state B) liquid state C) plasma state D) mesoscopic state
   3. The elastic behaviour of a liquid is characterized by its
      A) Young's modulus B) Rigidity modulus C) Bulk modulus D) Poisson's ratio
   4. Ultrasonic waves are produced by
      

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      A) electromagnetic induction B) electric tuning fork C) piezo electric effect D) inverse piezo electric effect
9. b. Write a note on fullerence. What are the applications of fullerences. (08 Marks)
10. c. Explain with principle, how the flaw in a solid can be detected by non-destructive method using ultrasonics. (08 Marks)

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