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VIT UNIVERSITY

(Estd. u/s 3 of UGC Act 1956)

School of Electronics Engineering (SENSE)

Discipline: B.Tech (ECE) Semester: II/IVSubject: EEE108-Network Theory Marks : 100 Time :

3.00 hours

I. A. 1. Given the sinusoid 5 sin( 4πt − 60 ), calculate its amplitude, phase, period, and frequency. (2)

2. Calculate the phase angle between v 1 = −10 cos(ωt + 50 ) and v 2 = 12 sin(ωt − 10 ). State which

sinusoid is leading. (2)

3. The voltage v = 12 cos( 60t + 45 ) is applied to a 0.1-H inductor. Find the steady-state current

throughthe inductor. (2)

4. Determine v o(t) in the circuit in Fig. 1 (4)

Fig. 1

B. Find i x in the circuit of Fig. 2 using nodal analysis. Also find power delivered to 10Ω resistance.(10)

Fig. 2

OR

C. Find v o in the circuit in Fig. 3 using the superposition theorem. (10)

Fig. 3

II. A. 1. Laplace transform (LT), a very powerful tool for analyzing circuits with sinusoidal or non-sinusoidal

inputs. (True / False) (1)

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2. Laplace transform is capable of providing us, in one single operation, the total response of the circuit

comprising both the natural and forced responses. (True / False) (1)

B. Find the initial current of a circuit having one ohm resistance with applied voltage v(t)= e−2t cos 10t ,using Laplace transform technique. (4)

C. Find v o(t) in the circuit in Fig.4, assuming zero initial conditions. (8)

Fig.4

D. Realize the function G(s) =V o(s)/ V i(s) =4s /( s2 + 4s + 20) using the circuit in Fig.5. Select R =2 Ω, and determine L and C.

(6)

Fig.5

III. A. Determine the y parameters for the two-port shown in Fig.6 and draw the equivalent circuit of y

parameters. Fig.6

B. The ABCD parameters of the two-port network in Fig.7 are A=4, B=20Ω, C=0.1 S and D=2. The output

port is connected to a variable load for maximum power transfer. Find RL and the maximum power

transferred. (10)

Fig.7OR

C. Determine the Z parameters of the network shown in Fig.8 using network interconnection concept. (10)

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Fig.8

IV. A. Let the function f (t) in Fig.9a be the voltage source v s (t) in the circuit of Fig.9b. Find the response v o(t)of the circuit.

(10)

Fig 9a Fig 9b

B. Determine the average power supplied to the circuit in Fig. 10 if

i(t) = 2 + 10 cos(t + 10 ) + 6 cos( 3t + 35 ) A. (10)

Fig.10

V. A. Determine what type of filter is shown in Fig. 11. Calculate the corner or cutoff frequency. Take R = 2 k

Ω, L = 2 H, and C = 2 µF. (10)

Fig 11

B. 1. Design a low-pass active filter with a dc gain of 4 and a corner frequency of 500 Hz. (5)

2. Obtain the transfer function of a filter shown in Fig. 12 and identify the filter type and order. (5)

R C +

Vi L Vo

Fig.12