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B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2011.
Common to B.E./B.Tech. (ECE/CSE/IT/BIO-MED)
Second Semester
147201/EC2161 ELECTRIC CIRCUITS AND ELECTRON DEVICES
(Regulation 2010)
Time : Three hours Maximum : 100 marks
Answer ALL questions.
PART A (10 x 2 = 20 marks)
1. Define Super position theorem.
2. Explain Kirchoofs current law.
3. What is role in choice of Q-factor of a coil?
4. Compare parallel and series resonance.
5. Draw the energy band diagram for intrinsic and extrinsic
semiconductors.
6. What is zener breakdown?
7. Compare P-channel and n-channel JFET.
8. What is thermal runaway in semiconductor devices?
9. What is tunneling effect in diodes?
10. What are photovolatile cells?
PART B(5 x16 = 80 marks)
11. (a) (i) State and prove the maximum power transfer theorem
(12)
(ii) Find the equivalent resistance between the two points A and
B as shown in the fig. (4)
Or
(b) (i) Obtain the thevenins equivalent of network shown in fig.
between terminals X and Y. (12)
(ii) Draw the dual network of the network shown in the fig.
(4)
12. (a) (i) Derive the expression for the cut off and resonant
frequencies for parallel RL circuit. (12)
(ii) Derive the bandwidth for a parallel resonance circuit with
variable L value. (4)
Or
(b) (i) Determine expression of resonant frequency and Q-factor
of a series RLC resonant circuit. (6)
(ii) A series RLC circuit with resistance of 10 W, inductance of
0.1 H and capacitance of 50 m F is
supplied by voltage source of 50 V. Find resonant frequency and
the frequencies at which maximum
voltage appears across L and C. (10)
13. (a) (i) Derive the current equation for a PN-Junction diode.
(12)
(ii) Compare zener diode with PN Junction diode. (4)
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Or
(b) (i) Explain the operation of zener diode and plot its
characteristics. (12)
(ii) Discuss the effect of temperature on reverse saturation
current. (4)
14. (a) (i) Explain the principle and operation of CE transistor
based amplifier. (12)
(ii) Compare CE, CB and CC configuration. (4)
Or
(b) (i) Explain the operation of an Enhancement type MOSFET.
(12)
(ii) Compare BJT and FET. (4)
15. (a) (i) Explain the working and operation of SCR and plot
its characteristics. (12)
(ii) Write short notes on Photodiode. (4)
Or
(b) Write short notes on :(i) Laser diodes (4)
(ii) TRIAC (4)
(iii) UJT (4)
(iv) Photo conductive cells. (4)
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