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802302-3 Circuit Analysis II

1431/1432 Term 2

Groups 1 & 3

Final Exam

The Exam consists ofSIX Questions Time Allowed: 2 Hours

Question 1

a. Express the time-domain differential equation that describes the relation betweenthe current i(t) and the voltage vS(t) in the RL circuit shown in Figure 1. Assumingthat i(t) = 0, drive the s-domain representation of the circuit, and use this

representation to find an expression for i(t), t> 0.

b.

Find an expression forvo(t),t

> 0, in the circuit shown in Figure 2. Assume zeroinitial conditions.

Question 2

a. For the series RC circuit shown in Figure 3, express the source voltage vs inphasor form. Draw the impedance diagram of the load, and use phasor analysis tofind the steady-state current i and the voltage v across the capacitor in phasor form

and in time-domain representation.

b. For the circuit shown in Figure 3, assume that the frequency of the voltage sourceis allowed to change from zero to infinity. Find an expression for the magnitude

ofV in terms of the frequency, and sketch on semi-log scale the value of thisexpression versus frequency. Determine the frequency at which the magnitude of

Vreaches of its maximum value.

Question 3

a. Find Z in the AC network shown in Figure 4, given that Vo = 4 V .b. For the AC circuit shown in Figure 5, determine the value ofZL for maximum

power transfer from the source to the load. Determine the power transferred to the

load at that value ofZL.

Question 4

a. A 50-Hz AC voltage source Vs = 220 V delivers current Is = 10 A toan AC load network. Determine the power factor, the apparent power, the average

power, and the reactive power of the network. Determine the power-factorcorrection capacitor required to raise the power factor of the network to unity.

KINGDOM OF SAUDI ARABIA

Ministry of Higher Education

Umm Al-Qura UniversityCollege of Engineering and Islamic Architecture

Electrical Engineering Department

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b. In the series resonant circuit shown in Figure 6, R= 93.6 ,L = 14.9 mH, and C= 17 nF. Determine the resonant frequency, the quality factor, the bandwidth, and

the voltage drop at resonance on each of the three passive elements in phasorform, and in time-domain representation.

Question 5

a. For the filter shown in Figure 7,R= 120 ,L = 1.91 mH. What is the type of thefilter? Determine the cutoff frequency fcof the filter, and sketch semi-log scalethe phase angle by which Vo leads Vi versus frequency at 0.1fc, 0.5fc,fc, 2fc, 5fc,

and 10fc.

b. For the air-core transformer shown in Figure 8, the coupling coefficient k= 1.Find the value ofLs if the mutual inductance M = 80 mH. Find the induced

voltages ep and es if the flux linking the primary coil changes at the rate of 0.8Wb/s. Find the induced voltages ep and es if the primary current changes at the

rate of 0.2 A/ms.

c. A balanced three-phase -connected load is connected to a balanced three-phasethree-wire Y-connected generator having a phase voltage of 220 V. If the totalpower delivered to the load is 4800 W at 0.8 power factor lagging. Determine themagnitude of the line voltage, the magnitude of the line current, the magnitude of

the phase current of the load, and the phase impedance of the load.

Question 6

a. Find the Z parameters of the two-port network shown in Figure 9.b. Find the transmission parameters of the network shown in Figure 10 by

considering the circuit to be a cascade interconnection of three two-port networks,

each containing one passive element.

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