B.E./B.Tech.
DEGREE EXAMINATION, Nov/Dec 2010
Second
Semester
EC2151-
ELECTRIC CIRCUITS AND ELECTRON DEVICES
(Regulation
2008)
(Common
to Biomedical Engineering, Electronics and Communication Engineering and
Information Technology)
Time: Three
hours
Maximum: 100
Answer
ALL Questions
PART
A- (10 X 2 = 20 Marks)
1. State
Kirchoff's current law and voltage law.
2. State Superposition
theorem.
3. What is
quality factor?
4. Find the
resonant frequency in the ideal parallel LC circuit shown in figure.
5. Give the
expression for transition capacitance and diffusion capacitance of a PN diode.
6. Define
avalanche breakdown.
7. What is
"Early effect" in CB configuration and give its consequences?
8. Distinguish
clearly the difference between N with P channel FETs.
9. Give some
applications of tunnel diode.
10. What is meant
by photovoltaic cell?
PART
B- (5 X16 = 80 Marks)
11. (a) (i) State
Thevenin's and superposition theorems, mention one application. (8 Marks)
(ii) Find the
Thevenin's equivalent of the circuit shown in figure. (8 Marks)
(Or)
(b) (i) Consider
the circuit in figure. (12 Marks)
(1) If Rout =
3Kohm, find the power delivered to it.
(2) What is the
maximum power that can be delivered to any Rout?
(3) What two
different values of Rout will have exactly 20mw delivered to them?
(ii) State
maximum power transfer theorem. (4 Marks)
12. (a) In the
circuit shown in figure, determine the complete solution for the current when
the switch is closed at t =0. Applied voltage is v(t) = 400cos(500t + ^/4),
resistance R = 15ohm, inductance L = 0.2H and capacitance C = 3 Uf. (16 Marks)
(Or)
(b) (i) Explain
(using the relevant circuit) the double tuned circuit and derive the expression
for A and Mc. (10 Marks)
(ii) The tuned
frequency of a double tuned circuit shown in fig. is 10^4 rad/sec. If the
source voltage is 2v and has a resistance of 0.1 ohm, calculate the maximum
output voltage at resonance if R1= 0.01 ohm, L1= 2UH, R2 = 0.1 ohm and L2 =
25UH. (6 Marks)
13. (a) (i)
Derive the PN diode current equation. (8 Marks)
(ii) Explain how
the depletion region at a p-n junction is formed and explain with relevant
sketches for charge density, electric field intensity and potential energy
barriers at the junction. (8 Marks)
(Or)
(b) (i) Draw the
Zener diode characteristics and explain the working o Zener diode. (8 Marks)
(ii) Draw the
Zener regulation circuit and explain its function for input and output
regulation. (8 Marks)
14. (a) Explain
the input and output characteristics of a common emitter configuration with a
neat sketch. (16 Marks)
(Or)
(b) What is
MOSFET? Explain the construction and working principle of enhancement mode and
depletion mode MOSFET with a neat diagram. (16 Marks)
15. (a) What is
tunneling phenomenon? Describe the V-I characteristics and concepts of tunnel
diode with application. (16 Marks)
(Or)
(b) Explain the
negative resistance characteristics of Unijunction Transistor with neat sketch.
(16 Marks)