Question Paper: Applied Physics 2 Question Paper - May 17 - First Year Engineering (Semester 2) - Mumbai University (MU)

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## Applied Physics 2 - May 17

### First Year Engineering (Semester 2)

Total marks: 80

Total time: 3 Hours
INSTRUCTIONS

(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/m

^{2}acting normal to the direction of electron motion. Determine the radius of the path.