First Year Engineering (Semester 2)
Total marks: 80
Total time: 3 Hours
(1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Draw neat diagrams wherever necessary.
Solve any five question from Q.1(A, B, C, D, E)
1(A) Why the Newton's rings are circular and fringes in wedge shaped film are straight?
1(B) What is grating and grating element?
1(C) The core diameter of multimode step index fibre is 50μm. The numerical aperture is 0.25, calculate the number of guided modes at an operating wavelength of 0.75μm?
1(D) What is a population inversion state? Explain its significance in the operation of LASER/
1(E) What is diveragence of a vector field? Express it in Cartesian coordinate system.
1(F) What do you mean by thin flim? Comment on the colors in thin film is sun light.
1(G) An electron is accelerated through a potential difference of 18kV in color TV cathode ray tube. Calculate the kinetic energy and the speed of th electron.
2(A) Derive the conditions for maxima and minima due to interference of light transmitted from thin film of uniform thickness.
2(B) Differentiate between step index and graded index fibre An optical fibre has a numerical aperture of 0.20 and a refractive index of cladding is 1.59. Determine the core refractive index and the acceptance angle for the fibre in water which has a refractive index of 1.33.
3(A) Explain the experimental method to determine wavelength of spectral line using diffraction grating. What is the highest order spectrum which can be seen with monochromatic light of wavelength 6000A° by means of a diffraction grating with 5000 lines/cm?
3(B) Explain construction and working of He:Ne laser with neat fabel diagram.
4(A) Explain Cylindrical co-ordinate system. State the transformation realtion between Cartesian and Cylindrical co-ordinates.
4(B) Explain the concept of electrostatic fousing in election optics.
4(C) Two optically plane glass trips of length 10cm are placed one over the other. A thin foil thickness 0.01 mm is introduced between them at one end to form an air film. If the light used has wavelength 5900A° find the spearation between consecutive bright fringes.
5(A) With Newton's ring experiment explain how to determine the refractive index of liquid?
5(B) Using Spherical co-ordinate systems calculate the area of radius 2 cm.
5(C) What are different techniques to synthesis nanomerical? Explain one of them in detail.
6(A) With a neat diagram explain construction and working of Scanning electron microscope.
6(B) Explain the costruction and reconstruction of hologram with neat diagram.
6(C) An electron is accelerated through a potential difference of 5kV and enters a uniform magnetic field of 0.02wb/m2 acting normal to the direction of electron motion. Determine the radius of the path.