Optics B.Sc Question Paper : mlsu.ac.in

University : Mohan Lal Sukhadia University
Degree : B.Sc
Subject : Optics
Year : I
Document Type : Question Paper
Website : mlsu.ac.in

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MLSU Optics B.Sc Question Paper

First Year Examination of the Three Year
Degree Course, 2001 (Faculty of Science)
PHYSICS Paper II (Optics)

Related : Mohan Lal Sukhadia University Atomic & Nuclear Physics B.Sc Question Paper : www.pdfquestion.in/5808.html

Time – Three Hours
Maximum Marks – 50
Attempt Five question in all, selecting ONE question from each unit. All questions carry equal marks.

UNIT I

1. Deduce Newton’s formula for a converging lens forming a real image. What do you understand from Nodal points and Nodal planes-
OR
2. What do you understand by the term achromatism of a lens- Derive the condition of achromatism for two thin lensews of focal lengths f1 and f2 made of same material but separated by a distance.

UNIT II

3. (a) Discuss the coherence of an ordinary source of light and a lasersource of light. Can a two-level laser be constructed- 2+2+2
(b) In a michelson interferometer, 200 fringes cross the field of view when the movable mirror is displaced through 0.05896 mm. Calculate the wavelength of monochromatic light used.
OR
4. Explain the construction of a Febry-Perot interferometer and explain its action. Explain colour effects in Thin films. 3+3+4

UNIT III

5. Describe the construction of Half-Period zones. A circular opaque disc of diamerter 1 cm is placed at a distance of 1 meter from a point source of light ( = 6000 A). The diffraction pattern is observed at a distance of 2 meters from the disc. Calculate the number of Fresnel zones covered by the disc. 6+4
OR
6. Discuss the Fresnel diffraction pattern due to a straight edge. Give the necessary theory.

UNIT IV

7. (a) What do you understand by the resolving power of a telescope- Deduce an expression for resolving power of a telescope.

(b) Calculate the limiting angle ‘0’ which two distant separated star should subtend on the objective of one inch aperture telescope so as to be just resolved by it. ( 1 inch = 2.54 cm.) The effective wavelength of light is 5500 A.
OR
8. (a) Discuss Fraunh offer diffraction due to a single slit. Explain the basic difference between the diffraction spectra of a single slit and a plane transmission grating. 3+3

(b) A double slit is illuminated with light of wavelength = 4800 A. The slits are separated by 0.1 mm and the slit width is 0.020 mm. The Fraunhoffer diffractions pattern is observed on a screen 50 cm away from the slits. Calculate the fringe spacing.

UNIT V

9. Discuss the state of polarisation of emergentlight in following cases :-
(i) A plane polarised light falls normally on a half ave plate when vibration direction is at 45 degree with the optic axis of the plate, the optic axis being parallel to the face.

(ii) A plane polarised light falls normally on a quarter wave plate at an angle other than 45 degree with the optic axis which is parallel to the face of plate. (exclude 0 and 90)

(iii) A plane polarised light falls normally on a quarter wave plate at an angle-45 with the optic axix which is parallel to the face to plate.

Syllabus :
Paper-II : 1162 Oscillations, waves and Acoustics
UNIT – I :
Free oscillations of simple systems : Equilibrium; concept of potential well, small oscillations approximation, solutions, linear and transverse oscillations of a mass between two springs, diatomic molecule, reduced mass concept.

Damped and forced oscillations : Damped oscillations; critical damping, Q of an oscillator. Forced oscillator with one degree of freedom; Transient and steady state oscillations, resonance energy absorption, low and high frequency responses.

UNIT – II :
Free oscillations of system with two degrees of freedom : Two dimensional oscillator; normal modes, longitudinal and transverse oscillation of coupled masses, energy transfer between modes, coupled pendulum.

Fourier analysis : Fourier series and Fourier coefficients; simple examples (square wave, saw-tooth wave, half and full wave rectifier), use of exponential representation for harmonic oscillations, expression for Fourier coefficients