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Tuesday, November 19, 2013

Network Theory online bits cont

I Choose the correct alternative:
1. A periodic function f(t) with time period T repeats itself after half time period T/2. The Fourier series of f(t) would contain [ ]
(a)cosine terms only (b)odd harmonic terms only
(c)even harmonic terms only (d)sine terms only
2. A given function f(t) can be represented by a Fourier series if it is [ ] (a)periodic (b)single valued
(c)having a finite number of maxima and minima in any one period (d)all the above
3. Which of the following periodic function possesses even symmetry [ ]
(a)cos3t (b)sint (c)tcos5t (d)(t+t2+t3)
4. For a prototype low pass filter, the series and shunt elements respectively are [ ] (a)capacitive and inductive (b)inductive and capacitive
(c)series combination of capacitive and inductive (d)resistive and inductive
5. The number of possible combinations generated by four variables taken two at a time in a two-port network is [ ]
(a)four (b)six (c)two (d)eight
6. Which parameters are widely used in transmission line theory ? [ ]
(a)Z parameters (b)Y parameters (c)ABCD parameters (d)h parameters
7. The impedance parameters of a two port network are Z11=6Ω, Z22=4Ω, Z12=Z21=3Ω. Compute the A and B parameters respectively. [ ]
(a)6/3, 5 (b)5, 6/3 (c)5, 8/3 (d)6/3, 9
8. The Z-parameters of a two port network are Z11=10Ω, Z12=Z21=5Ω, Z22=15Ω. The equivalent T network parameters Za, Zb and Zc are [ ]
(a)5Ω, 15Ω,8Ω (b)15Ω, 5Ω,9Ω (c)3Ω, 2Ω,23Ω (d)5Ω, 10Ω, 5Ω
9. It is possible to express the elements of the П-network in terms of Y parameters or ABCD parameters. The Y1 can be obtained from [ ]
(a)(D-1)/B (b)1/B (c)(A-1)/B (d)both b and c
10. The port currents of a two port network are given by I1=2.5V1-V2 and I2= -V1+5V2. The equivalent П network [ ]
(a)1.5, 1, 3 (b)1.5, 1, 6 (c)1.5, 1, 4 (d)1.5, 8, 2

II Fill in the blanks:
11. The ABCD parameters of a network are A=6/5, B=17/5, C=1/5, D=7/5. The image parameter ZI1 is ____________.
12. When two networks, x and y are connected in series the Z11 parameter of the combined network is ______________.
13. In a two port bilateral network, if three transmission parameters are known, the fourth may be found from the equation _________________.
14. For given Z11=3Ω, Z12=1Ω, Z21=2Ω and Z22=1Ω, the determinant of admittance matrix is _________.
15. The Fourier Transform of a unit step function is given by ____________.
16. Acomplex voltage waveform is given by V=120sinwt+36sin(3wt+П/2)+12sin5wt. It has a time period of T seconds. The percentage fifth harmonic contents in the waveform is _____.
17. The shunt element in band pass filter is ___________________________.
18. A constant K-low pass filter is designed to cut off at a frequency of 1KHz and the resistance of the load circuit is 50 Ω. The required values of L and C is __________ and ____________.
19. The condition for a network with Z1 series impedance and Z2 shunt impedance to have a pass band is _________________.
20. The design value of L for a prototype high pass filter with a design impedance Ro and cut-off frequency fc is given by _____________
I Choose the correct alternative:
1. b
2. d
3. a
4. b
5. b
6. b
7. c
8. a
9. a
10. c
II Fill in the blanks:
11. 3.817ohms
12. Z11=Z11x+Z11y
13. AD-BC=1
14. 1
15. 1jω
16. 10
17. parallel combination of L and C
18. 16mH and 6.4μF
19. -1<Z1/4Z2<0
20. Ro/4Пfc

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