Applied Physics 1 - Dec 2011

First Year Engineering (Semester 1)

TOTAL MARKS: 60
TOTAL TIME: 2 HOURS (1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Use suitable data wherever required.
(4) Figures to the right indicate full marks.

Answer any five :-

1 (a) Draw the following planes (121), (100), (111)(3 marks) 1 (b) State any three applications of superconductivity(3 marks) 1 (c) How Lissajous figure are used to determine phase difference?(3 marks) 1 (d) What are ultrasonic waves? State magnetostriction effect.(3 marks) 1 (e) State Sabine's formula.(3 marks) 1 (f) Calculate atomic packing factor for FCC crystal structure ?(3 marks) 1 (g) Show the position of Fermi level in intrinsic semiconductor, p-type semiconductor and n-type semiconductor.(3 marks) 2 (a) Explain Dimond crystal structure with proper diagram. Calculate the number of atoms per unit cell, atomic radius and atomic packing factor for diamond unit cell.(8 marks) 2 (b) What is cavitation effect? Kind the natural frequency of vibration of quartz plate of thickness 2mm,. Given: Young's modulus for quartz 8 x 10¹⁰ N/m² and density 2650 kg/m³. Calculate the change in thickness required if the same plate is to be used to produce ultrasonic waves of 3 MHz.(7 marks) 3 (a) Explain reverberation and reverberation time. Explain various methods for design of good acoustics.(8 marks) 3 (b) What is lattice parameters? Aluminium has density 2.7 gm/cm³. It has atomic weight 27 and lattice parameter is 4.05 A?. Determine the type of crystal structure followed by Aluminium and calculate the atomic radius. Given Avogadro's number N_A = 6.023 x 10²³/gm mole.(7 marks) 4 (a) what is superconductivity and critical temperature? Descibe type I and type II superconductor.(8 marks) 4 (b) Define mobility of charge. Find resistivity of germanium at 300 ?K. Given density of carriers is 2.5 x 10¹⁹/m². Mobility of electron is 0.39 m²/V-Sec and mobility of hole is 0.19 m²/V-Sec. Charge of electron is 1.6 x 10¹⁹C.(7 marks) 5 (a) State Hall effect and what is the signification of hall effect? N-type Ge sample has donor concentration 10²¹ atoms/m³. What hall voltage would you expect if current 1 x 10^-3 A and if 0.5 magnetic field is applied across 2 mm thick sample.(8 marks) 5 (b) What is piezoelectric effect? Explain with neat labeled diagram the construction and working of Piezoelectric oscillator.(7 marks) 6 (a) State and explain terms in Bragg's law of X-ray diffraction. Calculate the glancing angle on cube (100) of rock salt having lattice constant 2.84 A? corresponding to first order diffraction maximum for X-ray of wavelength 1.541 A? (8 marks) 6 (b) Explain construction and working of CRO.(7 marks)

Solve/Explain any three;

7 (a) A class room has dimension 20 x 15 x 10 m³, the reverberation time is 3 sec. calculate total absorption of its surfaces and average absorption coefficient.(5 marks) 7 (b) Liquid crystal and different phase of liquid crystal (5 marks) 7 (c) Point defects in crystal (5 marks) 7 (d) Meissner effect(5 marks)