Anna University Chennai 2005 B.Tech EI 132 — ELECTRON DEVICES - - Question Paper

B.E. DEGREE exam.
Second Semester
Electronics and Instrumentation Engineering
EI 132 — ELECTRON DEVICES
(Common to Instrumentation and Control Engineering)
Time : 3 hours Maximum : 100 marks
ans ALL ques..
PART A — (10 ´ two = 20 marks)
1. Draw the basic structure of a CRT.
2. An electron is injected perpendicularly into a uniform magnetic field of flux density 0.01 Wb/m2 with an initial speed of 107m/s. What will be the radius of the circular path that the electron describes?
3. Draw the energy band diagram of n kind and p kind semiconductor.
4. Compute the value of diffusion length in a single crystal germanium having 100 if the diffusion constant is 47 cm2/sec.
5. Mention the important features of power transistor.
6. What is Early effect?
7. Draw the equivalent circuit and the V–I characteristics of UJT. Mention the important characteristic of the identical.
8. Draw the high frequency equivalent circuit of FET in common source configuration.
9. What is an LCD? Mention its merits and demerits.
10. Discuss briefly about the operation of photo diode.
PART B — (5 ´ 16 = 80 marks)
11. (i) Explain about electrostatic deflection employed in CRT. Derive the necessary expressions. (10)
(ii) An electron enters the space ranging from 2 parallel plates A and B through a small hole in A with an energy of 200 eV at an angle of 60° to A. compute the uniform magnetic flux density needed to reason the electrons return through a different hole set in A at a distance of 0.08 mt from the point of entrance and lying in the identical plane as the initial velocity. (6)
12. (a) (i) Derive continuity formula. elaborate its uses? (10)
(ii) The resistivity of intrinsic germanium at 300°K is 0.47 ohm–mt. compute the intrinsic density of electrons and holes if the hole and electron mobilities in germanium are 3600 cm2/volt–sec and
1700 cm2/volt–sec. Also compute the diffusion coefficient for holes and electrons in germanium at 300°K. (6)
Or
(b) (i) Explain about Schottky barrier diode. (10)
(ii) The breakdown voltage of the diode is 10 V. obtain the value of for the currents and voltage specified. (6)

13. (a) (i) A silicon transistor shown in circuit has an . obtain the region of operation of transistor. obtain the value of for which the transistor comes out of saturation. (10)

(ii) Derive hybrid model of a transistor in common emitter configuration. (6)
Or
(b) Describe the operation of a bipolar junction transistor as a switch. How will you improve its performance if it is to be used for high frequency applications? Suggest a method.
14. (a) Draw the volt–ampere characteristic of a JFET and discuss about every of the regions of operations of the identical with relevant equations.
Or
(b) What is a bilateral diode switch? discuss.
15. (a) What is a charge transfer device? From the basic principle, discuss its operation.
Or
(b) With relevant diagrams, define about the operation of a solar cell.

Earning:   Approval pending.