Kurukshetra University 2007 B.Tech Electronics and Communications Engineering Physics-2nd - Question Paper

Physics-II
Paper: Phy-102E
Time: 3 Hours
Maximum Marks: 100

Note :- Attempt any 5 ques. in all, selecting at lowest 1 ques. from every unit.

UNIT-I

1.(a) elaborate Bravais space Lattices ? explain the details of al crystal systems and Bravais lattices. [8]

(b) For a simple cubic lattice compute

d100 : d110: d111 [6]

(c) Draw the subsequent planes:

(1 one 0), (1 one 1), (1 one 0) [6]

2. (a) explain in detail experimental Dray diffraction methods fo determining crystal structure. [12]

(b) explain briefly different 'point defects' in solids. Why are they called so ? [8]

UNIT-II

3. (a) Prove that wave group associated with a moving particle travels with the identical velocity as that of the particle. [14]

(b) Differentiate ranging from \|/ and | \|/2 |. [6]

4. (a) What is meant by Fermi energy ? compute its value for free electron gas at O K and mention its significance. [12]

(b) Use the Fermi distribution function to find the value of F(E) for E - EF= 0.01 eV at 200 K. [8]

UNIT-III

5. explain the motion of electron in a periodic field of a crystal. Show that effective mass of an electron in a crystal is inversely proportional to the 2nd derivative of the E-K curve. Under what conditions the effective mass of an electron can become +ve, -ve and infinity ? [20]

6.(a) Prove that at absolute zero, all the states above Fermi level EF are empty when the temperature is raised above absolute zero. [10]

(b) Distinguish ranging from metals, semiconductors and insulators on the basis of band theory and show that the effective number of free electrons in a completely filled band vanishes. [10]

UNIT-IV

7.(a) describe atomic magnetic moment and explain orbital diamagnetism. [12]

(b) Derive London's equations with reference to super conductivity. [8]

8.(a) discuss a photovoltaic cell and provide its characteristics.What is Fill Factor ? [10]

(b) What is the effect of traps on photoconductivity ? discuss. [10]

Earning:   Approval pending.