Name of the Organisation : Institute Of Aeronautical Engineering
Exam : B.Tech I Semester End Examinations
Category : Common for II Semester (AE, ME and CE)]
Subject : Modern Physics
Document Type : Previous Question Paper
Website : https://www.iare.ac.in/?q=node/2222
Download Previous/ Old Question Papers :
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IARE B.Tech Modern Physics Previous Question Paper
B.Tech I/II Semester Supplementary Examinations – July, 2017
Regulation : IARE – R16
Common for : II Semester (AE, ME and CE)
Related : Institute Of Aeronautical Engineering B.Tech Environmental Studies Previous Question Papers : www.pdfquestion.in/26087.html
Time: 3 Hours
Max Marks: 70
Instructions
** Answer ONE Question from each Unit
** All Questions Carry Equal Marks
** All parts of the question must be answered in one place only
UNIT – I
1. (a) Illustrate FCC crystal structure. Distinguish between SC and BCC crystal structures. [7M]
(b) Show that the maximum radius of the sphere that can just fit into the void at the body center of FCC structure coordinated by the facial atoms is 0.414 r where r is the radius of the atom.[7M]
2. (a) Derive an expression for the interplanar spacing between two adjacent planes of Miller indices (h k l) in a cubic lattice of edge length ‘a’. [7M]
(b) Explain the unit cell and bravias lattice with neat figures. Sketch the following plane in a cubic unit cell (1 1 2), (1 2 1), (1 0 1). [7M]
UNIT – II
3. (a) Describe with suitable diagram the powder method of determination of crystal structure. [7M]
(b) A beam of X-rays of wavelength 0.071 nm is diffracted by (110) plane of rock salt with lattice constant of 0.28 nm. Find the glancing angle for the second order diffraction. [7M]
4. (a) What is Burger’s vector? Distinguish between edge dislocation and screw dislocation. [7M]
(b) What is the angle at which the third order reflection of X-rays of 0.79 A0 wavelength can occur in a calcite crystal of 3:08 10??8 cm spacing? [7M]
UNIT – III
5. (a) Explain the construction and working of a semiconductor diode laser. [7M]
(b) Calculate the ratio of the stimulated emission rate to the spontaneous emissionrate for an incandescent lamp operating at a temperature of 1000K assuming the average operating wavelength to be 0:5m. [7M]
6. (a) Explain the three major engineering applications of laser. [7M]
(b) What are principles of sensors. Find the ratio of population of two energy levels in a laser if the transition between them produces light of wavelength 694.3nm. Assume the ambient temperature to the 270C. [7M]
UNIT – IV
7. (a) What is the principle of optical fiber? Distinguish between Step index and graded index fibers. [7M]
(b) Calculate the refractive indices of core and cladding materials of an optical fiber if its numerical aperture is 0.22 and relative refractive index difference is 0.012. [7M]
8. (a) What is attenuation? Explain the factors contributing to the fibers loss. [7M]
(b) Define the terms [7M]
i. refractive index of profile.
ii. fractional index change.
iii. angle of acceptance.
iv. The refractive indices of core and cladding are 1.5 and 1.48 respectively in an optical fibre. Find the numerical aperture and angle of acceptance.
UNIT – V
9. (a) Explain interference in thin films and obtain conditions for bright band and dark band. [7M]
(b) Newton’s rings are observed in the reflected light of wavelength 5000 A0. The diameter of the 10th dark ring is 0.5 cm. Find the radius of curvature of the lens used. [7M]
10. (a) Obtain an expression for the radius of the nth dark ring in case of Newton rings. [7M]
(b) In a grating show that only first order is possible if the width of the grating element is less than twice the wavelength of light. [7M]
May, 2017 :
Regulation: IA-R16
UNIT – I :
1. (a) Define coordination number and atomic packing factor. Calculate the atomic packing factor for SC and BCC structures. [7M]
(b) Draw and explain the structure of diamond with a neat sketch and show that atomic packing factor of diamond is 0.34. [7M]
2. (a) DHow do you find Miller indices of a given plane? An X-ray beam of wavelength 0.7 Ao undergoes minimum order, Bragg reflection from the plane (3 0 2) of cubic crystal at glancing angle 350. Calculate the lattice constant. [7M]
(b) Explain the unit cell and bravias lattice with neat figures. Sketch the following plane in a cubic unit cell (1 1 2), (1 2 1), (1 0 1). [7M]
UNIT – II :
3. (a) State and prove the Braggs law. [7M]
(b) Explain the Frenkel defect and Schottky defect with figures. [7M]
4. (a) Discuss the Laue equations with figure. [7M]
(b) What are the major applications of X-ray techniques in different fields. [7M]
UNIT – III :
5. (a) Explain the construction and working of a semiconductor diode laser. [7M]
(b) Explain the two conditions for laser action. A ruby laser omits a pulse of 20ns duration with average power per pulse being 100 KW. If the numbers of photons in each pulse is 6:98 10??14, calculate the wavelength of photons. [7M]
6. (a) Explain the working of a pressure sensor with a diagram. [7M]
(b) What are active and passive sensors? What are the advantages of optical fiber sensors? [7M]
UNIT – IV :
7. (a) What is acceptance angle? Obtain an expression for acceptance angle. [7M]
(b) Calculate the numerical aperture and acceptance angle for an optical fiber with core and cladding refractive indices being 1.563 and 1.498 respectively. [7M]
8. (a) What is attenuation? Explain the factors contributing to the fibers loss. [7M]
(b) Explain the modes of propagation of optical fibers with figure. A fiber with an input power of 9 dBm has a loss of 1.5 db/km. If the fiber is 3000 m long, what is the output power. [7M]
UNIT – V :
9. (a) Obtain the expression for interference due to reflected light in thin films. [7M]
(b) what is diffraction of light? A diffraction grating used at normal incidence gives a line (5400 Ao) in a certain order superposed on the violet line (4000 Ao) of the next higher order. If the angle of diffraction is 300, how many lines per cm are there in the grating? [7M]
10. (a) Distinguish between interference and diffraction. In a Newton’s rings experiment, show that the rings get closer as the order increases. [7M]
(b) Calculate the thickness of the air film at 10th dark ring in a Newton’s rings system viewed normally by a reflected light of wavelength 500 nm.The diameter of the 10th dark ring is 2 mm. [7M]