Question Paper: Engineering Physics : Question Paper Dec 2014 - First Year Engineering (Semester 1) | Pune University (PU)
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## Engineering Physics - Dec 2014

### First Year Engineering (Semester 1)

TOTAL MARKS:
TOTAL TIME: HOURS

### Answer any one question from Q1 and Q2

1 (a) Prove that in Newton's ring by reflected light the diameter of bright ring is proportional to square root of the odd natural numbers.(6 marks) 1 (b) Distinguish between musical sound and noise.(3 marks) 1 (c) A monochromatic beam of light of wavelength 5893° A° is incident normally on the top of a glass which is coated by transparent material MgF2 having R.I. 1.38. Calculate smallest thickness of the MgF2 layer which will act as a non reflecting surface.(3 marks) 2 (a) Define magnetostriction effect. Explain how magnetostriction oscillator is used to produce ultrasonic waves, with the help of neat ckt. Diagram.(6 marks) 2 (b) What is diffraction? What are the types of diffraction ? Distinguish between them (any two point).(3 marks) 2 (c) The average reverberation time of a hall is 1.5sec, and the area of interior surface is 3340m2. If the volume of the hall is 13000m3. Find the absorption coefficient.(3 marks)

### Answer any one question from Q3 and Q4

3 (a) Explain the construction and working of Ruby laser with the help of energy level diagram.(6 marks) 3 (b) Explain Fermi Dirac probability distribution function with the meaning of each symbol in it.(3 marks) 3 (c) Calculate the conductivity of pure silicon at room temperature when the concentration of charge carriers is
1.6×1010/cm3. Given that μe=1500 cm2/V.Sec, μn=500 cm2/V.Sec.
(3 marks)
4 (a) Explain Hall effect. Derive the equation of Hall voltage and Hall coefficient.(6 marks) 4 (b) Explain propagation of light in a doubly refracting crystal when the optic axis is parallel to the crystal surface, with the help of neat diagram.(3 marks) 4 (c) How should the polariser and analyzer be oriented to reduce the beam of light to i) 50% ii) 25% of its original intensity.(3 marks)

### Answer any one question from Q5 and Q6

5 (a) Deduce Schroedinger time independent wave equation.(6 marks) 5 (b) Define group velocity. Show that the group velocity of matter wave is equal to particle velocity.(4 marks) 5 (c) Calculate the de Broglie wavelength of electron having kinetic energy 1 KeV.(3 marks) 6 (a) State Heisenberg's uncertainty principle and prove it by thought experiment of electron diffraction at a single slit.(6 marks) 6 (b) What is wave function ? Explain what is normalization of wave function.(4 marks) 6 (c) An electron is trapped in a rigid box of width 2A°. Find its lowest energy level.(3 marks)

### Answer any one question from Q7 and Q8

7 (a) Explain critical field of a superconductor and give any three points to differentiate type-I and type-II superconductors.(6 marks) 7 (b) Explain the applications of nanoparticles in automobile and electronic industry.(4 marks) 7 (c) Explain electrical properties of nano-particles.(3 marks) 8 (a) Explain the synthesis of nanoparticles in automobile and electronic by colloidal route with diagram.(6 marks) 8 (b) Explain the Meissner effect. What important property of superconductor it explain.(4 marks) 8 (c) Explain two applications of superconductivity.(3 marks)