03.11.1998

EP 425

FIRST MIDTERM

1. i -) (4 Pts.) Perform the necessary operations;

a-) (1-j2)+(-1-j2) b-) (1+j5)x(4+j2) c-) d-)

ii -) (7 Pts.) Convert the following complex numbers from rectangular to polar or polar to rectangular;

a-) 1+j2 b-) –1+j2 c-) –5-j5 d-) e-) f-) g-)

iii-) (3 Pts.) Express the following waves as phasor;

a-) b-) c-)

iv-) (4 Pts.) The current through a 0.1 H coil is given. Find the sinusoidal expression for the voltage across the coil. Sketch the v and i curves.

v-) (4 Pts.) The voltage across a 1 mF capacitor is given. What is the sinusoidal expression for the current. Sketch the v and i curves.

vi-) (3 Pts.) Determine average power delivered to network having the following input voltage and current.

2. (25 Pts.) Calculate Z₄ of figure 1;

3. (20 Pts.) For the circuit of figure 1; obtain mesh circuit equations. Do not solve. (w=12.5 krad/sec)

4. (30 Pts.) Write the nodal equations for the circuit and solve for E₁

04.01.1999

EP 425

FINAL EXAMINATION

Time Duration : 120 Mins.

1. a-) For a practical tank circuit, derive the formulas of 3 dB (cut-off) frequencies w₁ and w₂.

b-) For the circuit shown in figure 1 find the resonance frequency w₀ at which E and I are in phase. What is the value of Z_T at this frequency ? Derive an expression for the quality factor Q of this circuit.

2. Find the waveform of the voltage v(t) across the current source in the circuit shown in figure 2 given that e(t)=2.828sin(5000t) V and i_s(t)=1.414cos(10000t) A.

3. Find the input impedance Z_in of the network shown in figure 3.

Good Luck

Dr.A.N.Yazıcı

22.11.1999

EP 425 (Elect.Circuit Analyses)

Time Duration : 100 Mins.

1. a-) Find the peak and effective values of the following sinusoidal waveforms

i- ) v=7.07sin377t Volt ii -) i=16x10^-3sin(377t-10⁰) Amper

b-) Find the phase relationship between the waveforms of each set

i -) v=2sin(wt-60⁰) ii -) v=35sin(wt-20⁰)

i=3sin(wt+30⁰) i=7cos(wt-110⁰)

c-) For the given pairs of voltages and currents in question 1b, indicate whether the element involved is a capacitor inductor, resistor, or combinations of them.

d-) In given 1, I=3sin(377t-20⁰)

i-) Find the sinusoidal expression for e

ii-) Find the value of the capacitance C

in microfarads

iii-) Find the average power loss in the

capacitor.

2. Write the mesh equations for the network of figure 2 and determine the current through the inductive elements.

Fig.2

3. Write the nodal equations for the network of figure 3.

.....12.1999

EP 425

Electrical Circuit Analyses

Second Midterm

Time Duration : 110 mins.

1. a-) Find the bandwidth (BW) of a series resonant circuit having a resonant frequency of 6 kHz and a Q_r of 15.

b-) Find the cutoff frequencies.

c-) If the resistance of the circuit ar resonance is 3 W, what are the values of reactances.

d-) What is the power dissipated at the half-power frequencies if the maximum current flowing through the circuit is 0.5 A?

2. For the parallel resonant network of given figure:

a-) Calculate the resonance frequency.

b-) Find the total impedance at resonance.

c-) determine the quality factor Q_r.

d-) Determine the 3-dB frequencies.

e-) Determine the bandwidth (BW).

f-) Calculate V_max and V_rms voltages.

g-) Decide whether this circuit can be

used as a good resonant circit or not.

3. a-) Draw and explain the graphs (V versus f) of filters which is used in electronic industries.

b-) Design a high-pass RC filter to have a corner frequency of 2 kHz, given a capacitor of 0.1 mF. Sketch the normalized gain A_v for a frequency range of 0.1f_c to 10 f_c.

Good Luck

Dr.A.N.Yazıcı

21.01.2000

EP 425 Electrical Circuit Analyses

Final Exam (Time Duration : 120 mins.)

Three Questions=100 Pts. Four Questions=130 Pts.

1. The Wheastone bridge can be used

to measure an unknown impedance

by balancing the bridge. The balance

condition is satisfied when I=0 A

and at this condition V_AB=V_AC

and V_CD=V_BD. Determine the

unknown component values

(R_X and L_X) required to balance

the bridges in Fig.1.

2. For the circuit in Fig.2, find the resonance

frequency w_r at which E and I are in

phase. What is the value of Z_T at this

frequency and simplify it also its

simplest form. Derive an expression for

the quality factor Q and BW of this circuit.

3. a. Design a radio receiver circuit (i.e a filter) that permits to pass the frequency from 88 MHz to 108 MHz.

b. Design a radio transmitter circuit (i.e a.tank circuit) that has a resonance frequency at 98 MHz. (Assume that all of the used resistors are 1 kW)

4. a. Sketch the idealized Bode plot for

A_V=V₀/V_i for the high pass filter

of Fig.3.

b. Using the results of part (a),

sketch the actual frequency

response for the same frequency

range.

c. Determine the decibel level at

f_c, f_c/2, and 2f_c,.

d. Determine the gain A_V=V₀/V_i

as f=f_c, f_c/2, and 2f_c.

Good Luck

Dr.A.N.Yazıcı

26.7.2001

EP 425 Electrical Circuit Analyses

First Midterm (Time Duration : 100 mins.)

(Summer School)

1-) a-) Express the following waves as phasor;

i-) ii-) iii-)

b-) The current through a 0.1 H coil is given. Find the sinusoidal expression for the voltage across the coil. Sketch the v and i curves.

2-) Calculate Z₄ of figure 1;

3-) Write the mesh equations for the network of figure 2.

Good Luck

Dr.A.N.Yazıcı