## 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 MgF_{2} having R.I. 1.38. Calculate smallest thickness of the MgF_{2} 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 3340m^{2}. If the volume of the hall is 13000m^{3}. 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

1.6×10^{10}/cm^{3}. Given that μ_{e}=1500 cm^{2}/V.Sec, μ_{n}=500 cm^{2}/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)