WBUT Question Papers EC 3rd Semester Circuit Theory and Networks 2009

        WBUT Question Papers Electronics Communication

B Tech 3rd Semester 2009

Circuit Theory and Networks

 

Time Allotted : 3 Hours               Full Marks : 70

The Figures In The Margin Indicate full Marks.

Candidates Are Required To Give Their Answers In Their Own Words

As Far As Practicable.

GROUP – A ( Multiple Choice Type Questions )

1. Choose The Correct Alternatives For Any Ten Of The Following :

I)   Laplace Transform Analysis Gives

A) Time Domain Response Only

B) Frequency Domain Response Only

C) Both (A) & (B)

D) Real Response Only.

ii)   If A Function Is Shifted By ‘T, Then It Is Correctly Represented As

A) F(T-T)U{T)

B) F(T-T) U(T-T)

C) F(T)U[T-T)

D) (T-T)F(T-T).

 

iii) The Equivalent Resistance Between & Y Of The Figure Shown Below Is R

A) 30£2                                               B) Son

C) 60Q                                                 D) Lofl.

 

Iv) If/( T) Is An Even Function. Then Its Fourier Transform F (Jw ) Is Given By

A) 2 /( T) Cos Wt Dt

B) 2/ ( T) Cos Wt Dt

C) 2 /( T) Sin Wt Dt

D)2/ (T) Sin Wt Dt.

 

V) The Thevenin’s Equivalent Resistance Of The Given Circuit With Respect To The Terminals A & B Is Equal To

5

-A A

•E J2

A) 2-66Q C) 8 Q

B) 3-2fl D) 12Q.

 

Vi) The Value Of The Unity Impulse Function 5 (T) At T – 0 Is

A)0                                                      B) Oo

C) 1                                                     D) Indeterminate.

 

Vii) The Number Of Links For A Graph Having ‘N’ Nodes & ‘B’

■ Branches Are

A)                                                        B-N+1            B) N – B + 1

C) B + N – 1                                      D) B + N.

 

Viii) The H Parameters H N & H 12 Are Obtained By

A) Shorting Output Terminals

B) Opening Input Terminals

C) Shorting Input Terminals

D) Opening Output Terminals,

 

Ix) The Convolution Of/(T) * G (T) Is

A)/(T) G (T-X ) DxTR

B)/(X)G(T-T) Dx

C)

D)

 

X) A Ramp Voltage V ( T) = 100 V Is Applied To An RC Series Circuit With R = 5 Kft & C = 4 Jif. The Maximum Output Voltage Across Capacitor Is

A) 0-2 Volt                                                   B) 2 0 Volt

C) 10 0 Volt                                                 D) 50 0 Volt.

 

Xi) The Voltage Across The Dependent Source Of The Circuit Shown Is

10

A)  8Z0′                                    B) 4 Z O’

C) 4 Z 90′                               D) 8 Z – 90*.

 

Xii) Relative To A Given Fixed Tree Of A Network

A) Link Currents Form An Independent Set

B) Branch Currents Form An Independent Set

C) Branch Voltages Form An Independent Set

D) Both (A) & (C).

GROUP -B ( Short Answer Type Questions )

 

Answer Any Three Of The Following

2.  In The Circuit Shown, Determine The Current I ( T) When The Switch Is Changed From Position 1 To 2. The Switch Is Moved From Position 1 To 2 At Time T = 0. Iw -±R ~±R Sov S.1 O ^2- 0- 5* H-

 

3. For The Circuit Shown Is The Figure, Find The Current In The 2Q Resistor By Using Thevenin’s Theorem.

 

Draw The Matrix : Graph Corresponding To The Given Incidence
– 1 0 0 0 + 1 0 + 1 0
0 – 1 0 0 0 0 – 1 + 1
A = 0 0 – 1 – 1 0 – 1 0 – 1
0 0 0 0 – 1 + 1 0 0
– 1 + 1 + 1 + 1 0 0 0 0
Determine The Cut Off Frequency For The High Shown Below. Pass Filter
CV2 M |T O I Xlf

6.  Find The Z-Parameters Of The Network Given Below :

 

GROUP -C ( Long Answer Type Questions )

 

Answer Any Three Of The Following. 3 X 15 = 45

7.  A) Explain With Example, Odd Symmetry & Even Symmetry Of Periodic Waveforms,

B)  Determine The Fourier Series For The Saw Tooth Waveform Shown Below

7

C)  Applying Fourier Transforms Determine The Output Voltage Across The Capacitor If The Excitation Is A Current Source Of (( T) = E “F U (T).

The Hybrid Parameters Of A Two-Port Network Shown In Figure Are H U = 1 Kft, H 12 = 0 003, H 21 = 100.

H 22 = 50 . Find V2 & Z Parameters Of The Network.

8. B)  What Are ABCD Parameters ? Prove That AD – BC = 1.

9.  A) For The Circuit Shown, Determine The Load Current 12 Using Norton’s Theorem.

B)  Convert The Active Network Shown In Figure To A Single Voltage Source In Series With Impedance.

10.   A) Draw The Circuit Diagram Of A First Order High Pass Alter And Find Out The Expression Of The Cut-Off Frequency. 5

B)  Draw And Explain The Characteristics Of Ideal Band-Pass & Band-Stop Filter.

C)  The Circuit Shown In Figure Is A Second Order Low-Pass Filter. Analyze The Circuit And Find Out The Cut-Off Frequency.

11.   A) Find The Laplace Transform Of The Periodic Waveform Shown In Figure.

B)  Define Convolution Theorem.

C)  Find Hr 1 { F, ( S ) F 2 ( S ) } By Using The Convolution Of The Following Functions

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