# 2010 Rajasthan Technical University B.Tech 1 Semester (back) Computer science & engineering "Physics" question paper

Question Paper Details:

University: Rajasthan Technical University
Course: B.Tech Computer science & engineering
Subject Physics
(Common to all branches of engineering)
Exam Year:  February 2010
Year or Semester: First year/ First Semester
Paper Code:
1E1003

Instructions to Candidates:
Attempt overall Five questions selecting one question from each unit. All questions carry equal marks.
Unit-I
1 a) With schematic diagram, explain the working of Michelson interferometer. How will you produce circular fringes with it? How will you measure the difference in wavelength between two closely spaced lines. [ Marks 6]
b) Give a brief account of:
i) Interference filters.
ii) Non- reflection coatings ( or Anti reflection coatings).  [Marks 6]
c) Newton’s rings are observed normally in reflected light of wave length 5.9×10^-5 cm. The diameter of the 10th dark ring is 0.50 cm. Find the radius of curvature of the lens and thickness of the film. [Marks 4]
OR

a)      Define specific rotation. Describe the construction and the working of a Laurent’s half shade polarimeter to determine optical rotation. [Marks 6]
b)      How would you produce and detect
i)                    Plane
ii)                  Circularly polarized and
iii)                Elliptically polarized light?    [Marks 6]
c)      A retardation plate of thickness 8.56×10^-7 m introduces a phase difference in the path of polarized light of wavelength 5890A0 . The principal refractive indices are Mue a=1.658, mue E=1.486. Find the nature of retardation plate. [Marks 4]
Unit-II
2. a) Dervie an expression for the intensity of diffracted light in the Fraunhoter’s diffraction due to a single  slit.   [Marks 6]
b) Describe and explain the Rayleight’s criterion of Resolution and obtain an expression for resolving power of a diffraction grating. [Marks 6]
c) What is the highest order spectrum. Which may be seen with monochromatic light of wave-length 6000A0 by means of a diffraction grating with 5000 lines/cm. [marks 4]
OR
a)      Describe the method of recording  the hologram and reconstruction of image from it. Can holography be studied with ordinary light? [Marks 6]
b)      Explain diffraction at a plane transmission grating. What particular spectra would be absent if the width of the transparencies and opacities of the grating are equal. [Marks 6]
c)      Calculate the minimum number of lines per cm in a 2.5 cm wide grating which will just resolve the sodium lines (5890A0 and 5896 A0) in the second order spectrum.  [Marks 4]
Unit-III
3. a) Define spatial and temporal coherence. Illustrate the concept of spatial coherence with the help of young’s double slit experiment. [Marks 6]
b) Explain the essential requirements for producing laser action. Describe the construction and working of semiconductor lasers. [Marks 6]
c) The coherence length for sodium light is 2.95×10^-2 m . The wave length of sodium light is 5890A0. Calculate
Number of oscillation & coherence time. [Marks 4]
OR

a)      What do you mean by numerical aperture of an optical fiber? Find the expression for the numerical aperture of a step index optical fiber. [Marks 6]
b)      Describe a He-Ne laser. How is population inversion achieved in this type of  laser. [Marks 6]
c)      Calculate the numerical aperture and acceptance angle of fiber with a core index of 1.54 and a cladding refractive index of 1.50. [Marks 4]
Unit-IV
4. a)  Describe Compton effect. Drive an expression for Compton shift. How does it support the particle nature of light. [Marks 6]
b) State Heisenberg’s uncertainty principle. Explain its validity by any thought experiment. [Marks 6]
c) Calculate the smallest possible uncertainty in position of an electron moving with velocity 3×10^7 m/s. [Marks 4]
OR
a)      Describe Heisenberg’s uncertainty principle and it to explain non-existence of electron in nucleus. [Marks 6]
b)      Derive Schrodinger time independent wave equation. What is the physical significance of wave function Y. [Marks 6]
c)      Explain the meaning of the terms degeneracy and tunneling. [Marks 4]
Unit-V
5. a) State the postulates of special theory of relativity and deduce from them the Lorentz transformation. [Marks 6]
b) Explain the concept of time dilation. Describe experimental verification of time dilation. [Marks 6]
c) Calculate the velocity of a particle having kinetic energy three times the rest mass energy. [Marks 4]
OR
a)      Describe construction and working of Geiger- Muller counter. Explain the terms dead time and quenching. [Marks 6[
b)      Derive Einstein’s mass energy relation and explain its importance. [Marks 6]
c)      An ionization chamber is charged to a potential 1000 volts. If its capacity be 50pf. By what percentage its chage would reduce in passing an a-particle producing 2×10^5 ion-pairs.