2010 Anna University Chennai B.E Computer Science and Engineering Ec 2151 — electric circuits and electron devices Question paper

B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2010
Second Semester
Computer Science and Engineering
EC 2151 — ELECTRIC CIRCUITS AND ELECTRON DEVICES
(Common to Biomedical Engineering, Electronics and Communication Engineering
and Information Technology)
(Regulation 2008)
Time : Three hours Maximum : 100 Marks
Answer ALL questions
PART A — (10 × 2 = 20 Marks)
1. Find Req of the restive network .
2. Determine the current drawn by the source as shown in
3. For the circuit shown in fig.3 determine the value of Q at resonance and
Bandwidth of the circuit.
4. A Series RC circuit consists of resistor of 10 and a capacitor of 0.1F as shown
in Fig.4. A constant voltage of 20v is applied to the circuit at t=0. Determine
voltage across resistor and capacitor.
5. State Mass-Action law.
6. Define diffusion capacitance.
7. Define Base width modulation and bring out its consequences.
8. Mention the advantages of MOSFET over JFET.
9. Draw the two transistor model of an SCR with its characteristic curve.
10. Under what principle does a photo voltaic cell work?
PART B — (5 × 16 = 80 Marks)
11. (a) (i) Use Thevenin's theorem to find the current through 5 resistor (Marks 8)
(ii) Find the voltage across 2 resistor in fig.6 by using super position
theorem. (Marks 8)
Or
(b) (i) Determine current flowing through the 5 resistor in the circuit
Norton theorem. (Marks 8)
(ii) Determine the maximum power delivered to the load in the circuit (Marks 8)
12. (a) (i) Find the complete solution for the current in a RLC circuit for a
sinusoidal input. (Marks 8)
(ii) The circuit consists of R = 10, L = 0.5 H and
C = 200 µ F. If the switch is closed when f = 30°. Determine the
current equation. (Marks 8)
Or
(b) (i) Consider the single tuned circuit
1. Resonant frequency
2. Output voltage at resonance and
3. Maximum output voltage.
Assume Rs>>wrL, and k=0.9. (Marks 8)
(ii) With neat diagram, obtain gain of a double tuned amplifier with
critical value of mutual inductance. (Marks 8)
13. (a) (i) State continuity equation and prove that concentration of changes
is independent of time with zero electric field. (Marks 8)
(ii) With neat diagram, explain the formation of PN junction and derive
its depletion width. (Marks 8)
Or
(b) (i) What is the breakdown mechanism found in Zener diode? Explain it
with neat diagram. (Marks 8)
(ii) Write detailed notes on space charge and diffusion capacitance. (Marks 8)
14. (a) Explain the construction and working principle of a JFET and obtain its
characteristic parameters. (Marks 16)
Or
(b) Explain the operation of a Depletion mode MOSFET and its comparison
over enhancement MOSFET with neat diagrams. (Marks 16)
15. (a) Discuss the construction and operation of a Tunnel Diode with neat
energy band diagram. (Marks 16)
Or
(b) Write detailed notes on:
(i) DIAC and TRIAC (Marks 5)
(ii) Photodiode and Phototransister (Marks 5)
(iii) LED and LCD (Marks 6)

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2008 Anna University Chennai B.E Electrical and Electronics Engineering B.E./B.Tech DEGREE EXAMINATION, APRIL/MAY 2008,Seventh semester,(Regulation 2004),Electrical and Electronics Engineering,EE 1001 – SPECIAL ELECTRICAL MACHINES Question papers

B.E./B.Tech DEGREE EXAMINATION, APRIL/MAY 2008
Seventh semester
(Regulation 2004)
Electrical and Electronics Engineering
EE 1001 – SPECIAL ELECTRICAL MACHINES
(Common to B.E.(Part Time) Sixth Semester regulation 2005)
Time : Three Hours Maximum: 100 marks
Answer all questions
PART A –(10x2=20)
1. What are the types of synchronous reluctance motor
2. List the application of vernier motor.
3. What are the main features of stepper motor which are responsible for its wide spread use?
4. Define the term stepping angle.
5. Draw the speed torque characteristics of switched reluctance motor.
6. What is the working principle of switched reluctance motor?
7. Give the merits of PMBL DC motor compared to conventional motor.
8. What is meant by peak recovery current in PMBLDC motor?
9. Synchronous machines with surface-mount magnets have very little difference between direct axis and quadrature axis inductances- why?
10. What is the magnitude of stator current in PMSM to achieve demagnetization?
11.
PART B – (5x16 = 80 marks)
11.(a) Explain the constructional details and working principle of synchronous reluctance motor. (16)
(OR)
(b) (i) draw and explain a typical torque – speed characteristics of a synchronous reluctance motors. (9)
(ii) Explain the working principle of vernier motor. (7)
12.(a) (i) Describe the operation of variable reluctance type stepper motor. Also explain about micro stepping. (9)
(ii) Explain the working of hybrid motor. (7)
(OR)
(b) (i) Explain torque versus stepping rate characteristics of a stepper motor. Also explain about slew range and damping. (10)
(ii) What is stepping angle? Calculate the stepping angle for a 3 phase 24 pole permanent magnet type stepper motor. (6)
13.(a)(i) Explain with neat diagram, the constructional details and working principle of switched reluctance motors. (9)
(ii) Write a note on power controllers used in switched reluctance motors. (7)
(OR)
(b) Explain with a neat block diagram, the microprocessor based control in switched reluctance motors. (16)
14.(a)(i) Explain the principle of operation of PMBLDC motor. (8)
(ii) Derive the emf equation of PMBLDC motor. (8)
(OR)
(b)(i) Explain with neat diagram and waveforms the full wave inverter based PMBLDC motor. (9)
(ii) Draw and explain the speed torque characteristics of PMBLDC motor. (7)
15.(a)(i) Derive the torque equation in PMSM.(8)
(ii) Explain with phasor diagram, the measurement of Ld and Lq in PMSM.(8)
(OR)
(b)(i) Explain the speed torque characteristics in PMSM. (8)
(ii) Explain the working of microprocessor based control in PMSM. (8)

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