Paper 5

Paper 5 : Waves and Optics

Old CBCS CORE 4

Syllabus

Propagation of light, its application and wave nature, concepts of wave motion, interference and its application, diffraction and its application.

Unit I

Geometrical optics: Fermat’s principle, reflection and refraction at plane interface, Matrix formulation of geometrical Optics, Cardinal points and Cardinal planes of an optical system, Idea of dispersion, Application to thick Lens and thin Lens, Ramsden and Huygens eyepiece. Wave Optics : Electromagnetic nature of light. Definition and properties of wave front Huygens Principle. Temporal and Spatial Coherence.

Unit II

Wave Motion: Plane and Spherical Waves, Longitudinal and Transverse Waves, Plane Progressive (Traveling) Waves, Wave Equation, Particle and Wave Velocities, Differential Equation, Pressure of a Longitudinal Wave, Energy Trans- port, Intensity of Wave. Superposition of two perpendicular Harmonic Oscillations: Graphical and Analytical Methods, Lissajous Figures (1:1 and 1:2) and their uses, Superposition of Harmonic waves.

Unit III

Interference: Division of amplitude and wave front, - Young’s double slit experiment, Lloyds Mirror and Fresnels Bi-prism, - Phase change on reflection: Stokes treatment, - Interference in Thin Films: parallel and wedge-shaped films, Fringes of equal inclination (Haidinger Fringes), Fringes of equal thickness (Fizeau Fringes), - Newton’s Rings: Measurement of wavelength and refractive index. - Interferometer : Michelson’s Interferometer-(1) Idea of form of fringes (No theory required), (2) Determination of Wavelength, (3) Wavelength Difference, (4) Refractive Index, and (5) Visibility of fringes, Fabry-Perot interferometer.

Unit IV

Fraunhoffer diffraction: Single slit, Circular aperture, Resolving Power of a telescope, Double slit, Multiple slits, Diffraction grating, Resolving power of grating.

Fresnel Diffraction: Fresnel’s Assumptions, Fresnel’s Half-Period Zones for Plane Wave, Explanation of Rectilinear Propagation of Light, Theory of a Zone Plate: Multiple Foci of a Zone Plate, Fresnel’s Integral, Fresnel diffraction pattern of a straight edge, as lit and a wire.

Text Books:
  • A text book of Optics N. Subhramanyam and BrijLal (S.Chand Publishing)
  • Optics - Ajoy Ghatak (McGraw Hill)
Reference Books
  • Optics- E. Hecht (Pearson)
  • Fundamentals of Optics- F. A. Jenkins and H. E. White(McGraw-Hill)
  • Geometrical and Physical Optics R. S. Longhurst (Orient Blackswan)
  • The Physics of Vibrations and Waves- H. J. Pain(John Wiley)
  • Optics P. K. Chakraborty.
  • Principles of Optics-Max Born and Emil Wolf (Pergamon Press)
  • The Physics of Waves and Oscillations-N. K. Bajaj (Mc Graw Hill)

Questions

2024 | +3-III-S-CBCS(MS)-Sc(H)-Core-IV-Phy-R&B

PART-I | Answer all the questions | 1x8
  • In zone plate intensity of image increases as the focal length decreases. (TRUE/FALSE)
  • In Fraunhoffer diffraction width of the central maximum is proportional to__ of light.
  • In Fabry-perot interferometer fringes are formed due to the division of ____ .
  • In Newton's ring fringe width decreases with the order of rings.(YES/NO)
  • Oscilloscope is application of _____.
  • Locus of the particles of the medium vibrating in _____ phase is known as wave front.
  • Huygens's eyepiece is fully free from____ aberration.
  • Refractive index x geometrical path = _____.
PART-II | within two to three sentences each | 1.5x8
  • Write properties of wavefront.
  • State Fermat's principle.
  • The wavelength of sodium light in vacuum is 5890 °A. Find the frequency and wavelength of light in water ($\mu = 1.33$).
  • What is intensity of wave? Write its S.I. unit.
  • Distinguish between plane wave and spherical wave.
  • Write the conditions for constructive and destructive interference.
  • Why are the Newton's rings circular?
  • Two real sources of light cannot act as coherent sources. Explain.
  • Find the radius of first zone of a zone plate of focal length 0.2m for a light of wavelength 5000 °A.
  • What is resolving power of grating?
PART-III | within 75 words each |(2x8)
  • Explain the rectilinear propagation of light.
  • Explain visibility of fringes in Michelson's Interferometer.
  • Explain Multiple Foci of a Zone plate.
  • Interference obey's law of conservation of energy. Explain.
  • Distinguish between Haidinger Fringes and Fizeau's fringes.
  • The amplitude of two coherent waves are in the ratio 2:1. Due to superposition find the ratio of maximum and minimum intensities of the fringes produced.
  • State the principle of superposition of N harmonic wave.
  • Distinguish between particle velocity and wave velocity.
  • A coaxial lens system placed in air has two lenses of focal lengths 3F and F separated by a distance 2F. Find the position first and second principle point.
  • Distinguish between Temporal and spatial coherence.
PART-IV | Answer within 500 words each | (6x4)

4) Describe the cardinal points and cardinal planes of an optical system.
OR
Using matrix method obtain the expression for equivalent focal length and position of cardinal points of Ramsden's eyepiece.

5) Derive an expression for energy transport in a plane progressive wave.
OR
What is Lissajous figure? Derive an expression for superposition of two S.H.M. having frequency ration 1:1 analytically.

6) Define Interference. Then derive an expression for Interference in wedge-shaped thin films.
OR
With neat diagram describe the principle, construction, and production of interference fringes with fabry-perot interferometer.

7) Explain Fraunhoffer diffraction at a double slit. Then derive an expression for intensity distribution and find the positions of maxima and minima.
OR
Describe the Fresnel's theory of half period zones for plane waves using Fresnel's basic assumption.

¤¤¤¤¤

Comments

Post a Comment