Circuit Theory and Networks Question Paper - Dec 17 - Electronics And Telecomm (Semester 3)

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Circuit Theory and Networks - Dec 17

Electronics And Telecomm (Semester 3)

Total marks: 80
Total time: 3 Hours INSTRUCTIONS
(1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Draw neat diagrams wherever necessary.

1.a. Find the Norton's equivalent circuit across the terminal a-b for the circuit shown in Figure No. 1.

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(5 marks) 00

1.b. Obtain the instantaneous value of currents through R and L and obtain the total current in terms of RMS value for the circuit shown in Figure No. 2. This circuit is energized by a sinusoidal a.c. voltage of v = 100sin (1000t+36) volt.

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(5 marks) 00

1.c. Determine the Z-parameters for the circuit shown in Figure No.3.

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(5 marks) 00

1.d. Differentiate between lossy transmission line and lossless transmission line with respect to

i. Equivalent circuit

ii. Propagation constant

iii. Attenuation constant

iv. Characteristics impedance

v. Input impedance

(5 marks) 00

2.a. Find the transmission parameters for the circuit shown in Figure No.4.

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(10 marks) 00

2.b. For network shown in Figure No.5, the switch is opened at t = 0, find v(t) for t > 0.

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(10 marks) 00

3.a. Find the Thevenin's equivalent circuit for the network shown in Figure No. 6 at the right of the terminal a-b.

(10 marks) 00

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3.b. A series RC combination, having an impedance of $\mathrm{Z}_{\mathrm{L}}=(450-\mathrm{j} 600) \Omega$ at 100MHz, is connected to a 300Ω transmission line. Calculate in meters the position and length of short circuited shunt stub designed to match this load to the line. Give any one solution and solve using Smith chart only.

(10 marks) 00

4.a. A driving point impedance is given by $Z_{L C}(s)=\frac{s\left(s^{2}+4\right)\left(s^{2}+6\right)}{\left(s^{2}+1\right)\left(s^{2}+5\right)}$ Obtain the first form of Cauer network.

(10 marks) 00

4.b. Find the voltage drop across the capacitor and the resistor for the circuit shown in Figure No. 7.

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(10 marks) 00

5.a. Find the Z parameters for the network shown in Figure No. 8

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(10 marks) 00

5.b. i. State properties of the positive real function (PRF).(5 marks)

ii. Check positive realness of the function $Y(s)=\frac{s^{2}+2 s+20}{s+10}$ with proper reason

(5 marks) 00

6.a. Find $\mathrm{V}_{\mathrm{C}}(\mathrm{t})$ and $\mathrm{I}_{\mathrm{L}}(\mathrm{t})$ in the circuit shown in Figure No. 9 assuming zero initial conditions.

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(10 marks) 00

6.b. A load impedance of $Z_{L}=(40+j 70) \Omega$ terminated 100Ω transmission line of length 0.3λ long. Use formulas and determine following parameters.

i. Find load admittance at the load end of transmission line. (2 marks)

ii. Find input impedance at the input port of transmission line. (4 marks)

iii. Find reflection coefficient at the load end of transmission line. (2 marks)

iv. Find voltage wave standing ratio (VSWR) along the transmission line. (2 marks)

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