Bangalore University 2007-2nd Sem B.E Engineering Chemistry I/ester , .06/.07 - Question Paper

I/II Semester B.E. Degree Examination, Dec.06/Jan.07
Common to All Branches
Engineering Chemistry

Time: three Hrs.] [Max. Marks: 100

Note: 1. ans any 5 full ques. choosing at lowest 2 ques. from
every part.
List of Constants:
i) Velocity of light C=3 x 10 eight m/s.
ii) Planck’s constant = h=6.626 x 10 –34 Js.
iii) Mass of neutron = 1.67 x 10 –23 J/K.
iv) Electron mass = 9.11 x 10 –31 kg.
v) Electrons charge = 1.6 x 10 –19 C.
vi) E0 permittivity of vacuum = 8.85 x 10 –12 Fm-1.

Part A

1. a. explain Planck’s radiation law (05 Marks)
b. discuss the duality of matter waves from the inferences drawn from photoelectric effect and Davisson-Germer effect (05 Marks)
c. describe group velocity and find an expression for the identical (05 Marks)
d. A particle of mass 0.5 Mev/C2 has kinetic energy 100 ev. obtain its de-Broglie wavelength, where C is the velocity of light. (05 Marks)

2. a. Show that electrons cannot exist in the nucleus of an atom. (07 Marks)
b. An electron has a speed of 6x1- five m/s with an inaccuracy of 0.01% With what fundamental accuracy can we locate the position of the elctron (05 Marks)
c. explain the wave functions, porbability densities and energy levels for a particle in a box. (08 Marks)

3. a. State Mathiessien’s rule and provide an account of the nature of total resistively both at high and low temperatures. (05 Marks)
b. Using the free electron model derive an expression for electrical conductivity in metals. (07 Marks)
c. discuss density of states. (03 Marks)
d. compute the drift velocity and thermal energy of electrons in a metal of thickness 1mm acorss which a potential difference of one volt is applied, at the temperature of 300K. The mobility of free electron is 40 cm2/v-2. (05 Marks)

4. a. discuss briefly the different kinds of polarization. (08 Marks)
b. Derive an expression for internal field in case of liquids and solids.
(08 Marks)
c. What is the polarization produced in sodium chloride
by an electric field of 600v/mm if it has a dielectric constant of 6?
(04 Marks)

PART B

5. A. discuss with sketches the basic principle of operation of lasers. (08 Marks)
b. define the construction and working of He-Ne laser, with energy level diagram. (08 Marks)
c. A laser medium at thermal equilibrium temperature 300K has 2 energy levels with a wavelength separation of one µm. obtain the ratio of population densities of the upper and lower level. (04 Marks)

Earning:   Approval pending.