Jawaharlal Nehru Technological University Hyderabad 2005 B.E Computer Science APPLIED PHYSICS I BTech Supplementary s, - Question Paper

Code No: NR10201 NR
I B. Tech Supplementary Examinations, June 2005
APPLIED PHYSICS
(For 2001 Batch only)
( Common to Electrical & Electronic Engineering, Electronics &
Communication Engineering, Computer Science & Engineering, Electronics &
Instrumentation Engineering, BioMedical
Engineering, info
Technology, Electronics & Control Engineering, Computer Science & Systems
Engineering, Electronics & Telematics and Electronics & Computer
Engineering)
Time: three hours Max Marks: 80
ans any 5 ques.
All ques. carry equal marks
? ? ? ? ?
1. (a) discuss photoelectric effect and derive an expression for photoelectric current[8]
density using FermiDivac
statistics in metals?
(b) State and write the relevance of Blochs theorem for the electron in periodic[8]
lattice.
2. (a) explain various sources of polarizability and find an expression for[8]
orientation polarizability subsequent Boltzman statistics.
(b) compute the polarizabiltiy of Argon atom if it’s relative permittivity at[8]
O 0 C and 1 atoms pressure is 1.0004.
3. (a) discuss how quantum theory of Para magnetism leads to the statement that
susceptibility varies inversely with temperature.[8]
(b) compute the relative permeability of a paramagnetic material with 3500
amp.m1
magnetization and 0.05 web.m-2 flux density.[8]
4. (a) Prove that the position of Fermi level with reference to intrinsic level determines
a semiconductor whether it is Ptype
a ntype.
(b) explain the ‘Law of Mass Action’ in semiconductors.[8+8]
5. (a) explain the mechanism of ‘Drift and Diffusion’ in semiconductors and derive
Continuity equations.
(b) Briefly discuss ‘Quasi Fermi Levels’.[8+8]
6. (a) discuss the working of semiconductor[8+8]
i. Thermistors and
ii. Lasers
(b) Detail the occurrence of phosphorescence and fluorescence in semiconductors.
7. (a) Write the working mechanism of solar cell and derive an expression for the
conversion efficiency in terms of fill factor.
(b) A solar cell with a short circuit current of 0.4 A has a reverse saturation
current of 1.5mA. compute its open circuit voltage.[8+8]
8. Write short notes on any 4 of the following:
(a) dc Joseph son effect
(b) Laser diode
(c) Adiabatic demagnetization
(d) Effective mass of electron
(e) IC capacitors
(f) Ferrites.
? ?[4+4+4+4]

Earning:   Approval pending.