Engineering Physics - May 2014

First Year Engineering (Set B) (Semester 1)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks. 1 (a) Show that group velocity less than the phase velocity in dispersive medium.(2 marks) 1 (b) What do you understand by normalization and orthogonal wave function. (2 marks) 1 (c) Calculate the uncertainly in momentum of a proton which is confined to nucleus of radius 10^-3 =cm. From this estimate the kinetic energy of the proton inside the nucleus.(3 marks)

Answer any one question from Q1. (d) & Q1 (c)

1 (d) Derive an expression for compton shift and wave length of scattered photon. Explain why compton shift is not observed with visible light?(7 marks) 1 (e) Obtain energy level and wave function expression for a particle trapped in infinitely deep square well potential.(7 marks) 2 (a) Explain the formation of colours when the white light is incident on a transparent thin film. (2 marks) 2 (b) Explain how double refraction phenomenon to produce plane polarized light and circularly polarized light.(2 marks) 2 (c) In a grating the sodium doublet (5890 Å, 5896 Å) is viewed in third order at 30° to the normal and is resolved. Determine the grating spacing and the total width of the rulings.(3 marks)

Answer any one question from Q2. (d) & Q2. (e)

2 (d) Describe construction and working of Michelson's inteferometer with near diagram. How it can be used to determine the wavelength of monochromatic light.(7 marks) 2 (e) Derive an expression for intensity distribution due the fraunhofer diffraction at a single slit. Show that the intensity of the first secondary maxima is about 4.5% of that of the principle maxima.(7 marks) 3 (a) Explain the volume energy and surface energy term of semi empirical mass formula.(2 marks) 3 (b) Write the necessary condition required for operation of linear accelerator.(2 marks) 3 (c) Discuss uses of mass spectrograph.(3 marks)

Answer any one question from Q3. (d) & Q3. (e)

3 (d) Describe construction and working of Betatron with neat diagram. Also derive the relation for Betatron condition.(7 marks) 3 (e) Explain the working of Geiger Muller counter. Estimate the average current in circuit when GM counter collect 10⁸ electrons per discharge at the counting rate is 460 counts/min.(7 marks) 4 (a) Explain effect of temperature on Fermi Dirac distribution.(2 marks) 4 (b) Explain the zener action of zener diode.(2 marks) 4 (c) Show that Hall coefficient is independent of applied magnetic field and is inversely proportional to the current density and electron charge.(3 marks)

Answer any one question from Q4. (d) & Q4. (e)

4 (d) Describe the behaviour of an electron in periodic potential using final expression of kroning panning model and explain the formation of energy bands.(7 marks) 4 (e) Explain meissner effect of super conductors. Discuss type I and type II super conductor.(7 marks) 5 (a) Explain how simulated emission is essential for lasing action.(2 marks) 5 (b) Write the advantage of multimode fibers over the single mode fibers.(2 marks) 5 (c) A multimode fiber has a core diameter of 70?m and the relative refractive index difference of 1.5 percent. It operate at the wave length of 0.85mm. The refractive index of the fiber is 1.46. Calculate
(i) The refractive index of the cladding
(ii) The normalized frequency V-number of the fiber and
(iii) The total number of guided modes in the fiber.(3 marks)

Answer any one question from Q5. (d) & Q5. (e)

5 (d) Describe the construction and working of He-Ne laser with energy level diagram.(7 marks) 5 (e) Explain inter modal dispersion. Derive expression for the delay difference to estimate the maximum pulse broading in time in step index fibre.(7 marks)