Bangalore University 2004 B.E Engineering Physics - Question Paper
Page No... 1
First/Second Semester B.E Degree Examination, July/August 2004
Common to all Branches
Time: 3 hrs.] [Max.Marks : 100
Note: 1. Answer any FIVE questions out of eight.
2. Each question carries equal marks.
3. Values of Constants :
Electron mass m 9.11 x 1031fc<7 Electron charge = 1.6xlO~19C Velocity of light c 3 x 108m/.s ;
Plancks constant h = 6.63 x 1034 J.5 Avagadros number, = 6.025 x 1026/Kmole
1. (a) Explain the duality of matter waves from the inferences drawn from Photo
electric effect and Davison Germer experiment. (5 Marks)
(b) Explain phase velocity and group velocity. Deduce the relation between them on the basis of superposition of waves. (io Marks)
(c) The position and momentum of 1 kev electron are simultaneously determined and if its position is located within I A0, what is the percentage of uncertainty in its momentum? (5 Marks)
2. (a) What are Eigen values and Eigen functions of a de-Broglie wave? Find Eigen
values and Eigen functions for a particle in 1-dimensional potential well of infinite height. (io Marks)
(b) Calculate the wave length associated with electrons whose speed is 0.01 of the speed of light. (7 Marks)
(c) Distinguish between Type I and Type II superconductors. Discuss briefly the BCS theory of superconductivity. (3 Marks)
3. (a) Explain the terms drift velocity. relaxation time and mean free path for free
electrons. (5 Marks)
(b) Explain density of states. Derive an expression for number of allowed states for a unit volume of solid. (io Marks)
(c) Show that the occupation probability at E Ep + AE is equal to the nonoccupation probability at E Ep - AE. (5 Marks)
4. (a) What is polarization and dielectric loss in dielectric materials? Explain the
dependence of polarizability and dielectric loss on frequency. (8 Marks)
.45 x 10 4m2 and the plates are
A parallel plate capacitor has an area of
(b)
separated by a distance of 2.45 x 10~"3m. across which a potential of 10V is applied. If a material with dielectric constant 6 is introduced between the plates, determine the capacitance, the charge stored on each plate, the dielectric displacement D and polarization. (5 Marks)
(c) Explain the properties and applications of ferrites.
(7 Marks)
5. (a) Explain the terms spontaneous emission, stimulated emission and population
inversion. Explain the construction and working of Ruby Laser. no Marks)
(b) Discuss the applications of lasers. (6 Marks)
(c) Find the ratio of population of two energy levels out of which one corresponds to xnet. stable stale, if Lhe wavelength of light emitted at 330K is 622 Snm.
4 Marks)
6. (a) Explain fiber-optic communication. Describe point to point communication
system using optical fibers with the help of a Block diagram. fs Marks)
(b) Explain attenuation of an optical fibre. A fibre with an input power o: 9.0fiW has a loss of 1.5dB/km. If the fibre is 3000m long, what is the output power?
'5 Marks)
(c) Explain the phenomena of production of mntinuus and characteristic X-ray spectrum. Derive the expression for Braggs law. n Marks)
7. (a) What are Miller, indices? Derive an expression for the interplanar spacing of
planes in terms of Miller indices in a cubic structure. (io Marks)
ib) Draw the following planes in a cubic unit cell (Oil), (102), (132) and (112).
(5 Marks)
(c) In an X-ray diffraction study, a radiation of wavelength 1.71 A0 was directed at a cubic crystalline sample. It was found that the first two Bragg reflections occur at angles of 30 and 3517/ respectively. Determine whether the crystal is BCC or FCC structure. (5 Marks)
8. (a) Explain density of states for various quantum structures. (5 Marks)
(b) Explain nano tubes and its applications by giving their physical properties.
(5 Marks)
(c) Explain smart materials with two examples. (3 Marks)
(d) What are composite materials? Give their classifications. (5 Marks)
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Attachment: |
| Earning: Approval pending. |
