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Semester : 02 Date :

Subject code : 09BECC204 Maximum marks :100

Subject Name : CIRCUIT THEORY Duration : 3.00 Hours

PART A (1x 20 = 20 Marks) - Time 30 Minutes

On Line Examination

PART B ( 5 X 16 marks) 2 Hrs

21.a (i) State and explain kirchhoffs current and voltage laws with suitable example. (8)

(ii) For the bridge network shown in Fig. 21.a. Calculate the current through each resistor,

and the current drawn from the supply.. (8)

(OR)

b. (i) Distinguish between mesh analysis and nodal analysis with example. (6)

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(ii) Find the equivalent resistance Req. of the network (see Fig.21.b ) at the terminals

a & b Using - and - transformations. (10)

22.a. (i) State and explain the Nortons theorem. . (4)

(ii) For the circuit shown in Fig.22.a. Find the value of RL that absorbs maximum

power from the circuit and the corresponding power under this condition. (12)

(OR)

b Use the superposition theorem to determine, for the network shown in Fig. 22.b. the

magnitude of the current flowing in the capacitor, (b) the p.d. across the 5

resistance, (c) the active power dissipated in the 20 resistance and (d) the totalactive power taken from the supply (16)

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23. a. A coil of inductance 159.2 mH and resistance 40 is connected in parallel with a 30 F

capacitor across a 240 V, 50 Hz supply. Calculate (a) the current in the coil and its phase

angle, (b) the current in the capacitor and its phase angle, (c) the supply current and its

phase angle, (d) the circuit impedance, (e) the power consumed, (f) the apparent power,

and (g) the reactive power. Draw the phasor diagram. (16)

(OR)

b. In the network of Fig. 23. use nodal analysis to determine (a) the voltage at nodes 1

and 2, (b) the current in the j 4 inductance, (c) the current in the 5 resistance, and

(d) the magnitude of the active power dissipated in the 2.5 resistance. (16)

24. a. (i) Derive the expression for current i for a series R-L Decaying transient network. (8)

(ii) A capacitor is charged to 100 V and then discharged through a 50 k resistor. If the

time constant of the circuit is 0.8 s, determine: (a) the value of the capacitor, (b) the

time for the capacitor voltage to fall to 20 V, (c) the current flowing when the

capacitor has been discharging for 0.5 s, and (d) the voltage drop across the resistor

when the capacitor has been discharging for one second. (8)

(OR)

b. Derive an expression with diagram for the resonance frequency of a (i) Series circuit

(ii) Parallel circuit. (16)

25. a. Two coils are connected in series and their effective inductance is found to be 15 mH.

When the connection to one coil is reversed, the effective inductance is found to be 10

mH. If the coefficient of coupling is 0.7, determine (a) the self inductance of each coil,

and (b) the mutual inductance. (16)

(OR)

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b. For the network shown in fig. 25, write a Tie-set schedule and then find all the branch

currents and voltages. Impedance between terminals AB = AC = BD = CD = 5 , and

BC = AD = 10 . (16)

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