### 131201(EE 1151) – CIRCUIT THEORY B.E./B.Tech. DEGREE EXAMINATION, MAY/JUNE 2009. Second Semester

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Reg. No. :
B.E./B.Tech. DEGREE EXAMINATION, MAY/JUNE 2009.
Second Semester
Electrical and Electronics Engineering
EE 2151 — CIRCUIT THEORY
(Common to Electronics and Instrumentation Engineering &
Instrumentation and Control Engineering)
(Regulation 2008)
Time : Three hours Maximum : 100 marks
PART A — (10 × 2 = 20 marks)
1. State Kirchoff ’s circuital laws.
2. Draw the V-I characteristics of ideal voltage source.
3. State super position theorem.
4. Calculate the value of RL, so that maximum power is transferred from battery.
(fig. 1)
Fig.1.
5. Define Bandwidth.
6. Define quality factor of a coil.
7. Find the Laplace transform of x (t) = u(t) +δ (t) .
8. Write the integro-differential equation of R-L-C series circuit with supply
voltage, E.
9. Calculate the power factor if V (t) = V sin(wt − 45°) m and
I (t) = I sin(wt −135°) m .
10. What are the advantages of 3-phase system over 1-phase system?
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PART B — (5 × 16 = 80 marks)
11. (a) For the circuit of fig. 2, find the current in each branch by Nodal method.
Fig.2.
Or
(b) Find the current in each branch of the circuit and the total power
consumed by the circuit of Fig. 3. Assume E = 50 sin (wt + 45°)
Fig.3.
12. (a) Find the Thevenin’s equivalent circuit at (a, b) (Fig.4)
Fig.4.
Or
(b) For the circuit shown in Fig. 5, find the current flowing through the 10
resistor. (16)
Fig.5.
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13. (a) For the parallel circuit shown in Fig. 6. find the Resonance frequency, f .
Fig.6.
Or
(b) (i) Explain the single tuned and double tuned circuit.
(ii) Derive the formula for mutual inductance in terms of coefficient of
coupling and self inductance.
14. (a) A series circuit consist of R-C in series with switch and supply voltage E,
the capacitor has initial charge 0 E . Find the transient voltage
V (t) C when the switch is closed at t = 0 .
Or
(b) A sinusoidal voltage of frequency 25 Hz is connected in series with switch
and R = 10 and L = 0.1 H. Calculate the transient current i (t).
15. (a) Prove that for balanced supply and unbalanced load of 3-phase system,
two wattmeters are sufficient to measure power.
Or
(b) (i) Derive the formula for total power consumed in unbalanced Y