ECE198-1 ELEX ans (1).docx

Republic of the Philippines MAPUA MALAYAN COLLEGES MINDANAO Gen. Douglas Mac Arthur Highway, Davao City ECE198-1 (ECE Correlation 2) Electronics \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-...

Republic of the Philippines MAPUA MALAYAN COLLEGES MINDANAO Gen. Douglas Mac Arthur Highway, Davao City ECE198-1 (ECE Correlation 2) Electronics \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- SET A *INSTRUCTION: Select the correct answer for each of the following questions. Mark [only one answer] for each item by shading the box corresponding to the letter of your choice on the answer sheet provided. STRICTLY NO ERASURES ALLOWED. Use pencil no. 2 only. [Do not detach the staple wire].* 1. 2. What type filter is used to block the passage of current for a narrow band of frequencies, while allowing current to flow at all frequencies above or below this band? A. low-pass filter C. band-pass filter B. band-reject filter\* D. high-pass filter 3. A transformer has 60 volts applied to its primary and 420 volts appearing across its secondary. If there are 800 turns on the primary, what is the number of turns in the secondary? A. 2300 turns B. 5600 turns \* C. 1300 turns D. 2500 turns 4. A resonant circuit has a lower critical frequency of 7 kHz and an upper critical frequency of 13 kHz. The bandwidth of the circuit is 5. A Silicon PN junction at a temperature of 20°C has a reverse saturation current of 10 pA. The reserve saturation current at 40°C for the same bias is approximately A. 30 pA B. 50 pA C. 40 pA\* D. 60 pA 6. How do you define I~DSS~? A. the maximum possible current with V~GS~ held at --4 V B. the maximum drain current with the source shorted C. the maximum possible current with V~GS~ held at 0 V \* D. the minimum possible drain current 7. Digital circuit that implements output that is HIGH (logic level 1) only if all of its inputs are HIGH. A. AND operation C. AND gate \* B. OR operation D. OR gate 8. Calculate the transconductance of a p-channel MOSFET enhancement type if the gate-source voltage VGS = -8 V , threshold voltage VT = -4 and a constant k = -0.3 mA/V^2^. A. 1.2 mS B. 2.4 mS \* C. 3.6 mS D. 7.2 mS 9. Calculate the permittivity of a material with relative permittivity of 5. A. 8.854 x 10^-11^ F/m B. 1/36π x 10^-9^ F/m C. 4.42 x 10^-11^ F/m \* D. 8.854 x 10^-12^ F/m 10. A magnetic flux of 25,000 maxwell in an area of 5 sq cm. results in flux density of A. 5,000 Gauss (G) \* B. 125,000 G C. 5,000 Tesla (T) D. 125,000 T 11. Find the current through R2 of the given circuit. http://www.indiabix.com/\_files/images/electrical-engineering/mcq8\_1007\_1.gif 12. Determine the ampere-turns when a 10 V battery is connected across a solenoid having 100 turns and a resistance of 5 Ω. A. 50 At B. 100 At C. 200 At \* D. 1,000 At 13. The terminal count of modulus-11 binary counter is \_\_\_\_\_\_\_\_\_. A. 1010\* C. 1000 B. 1001 D. 1100 14. The 2's complement of the number of 1010101 A. 0101011\* B. 0101010 C. 1101010 D. 1110011 15. What is the term for the out-of-phase power associated with inductors and capacitors? A. Effective power. B. Peak envelope power. C. True power. D. Reactive power. \* 16. You have an unlimited supply of 1-W, 100-Ω resistors. You need to get a 100-Ω, 10-W resistor. This can be done most cheaply by means of a series-parallel matrix of: 17. A full-wave center-tapped rectifier has a secondary maximum voltage of 20 Vm and a 4.7 kΩ load resistance. What is the dc load current for the circuit? A. 1.26 mA B. 629.8 mA C. 2.61 mA \* D. 1.4 mA 18. Determine the nature of the system, [\$\\frac{d\^{2}y(t)}{\\text{dt}\^{2}} + 2\\frac{dy(t)}{\\text{dt}} + 4y\^{3}\\left( t \\right) = x(t - 4)\$]{.math.inline} A. Static, linear, causal and time variant B. C. static, non-linear, causal and time variant C. Dynamic, non-linear, causal and time invariant D. dynamic, non-linear, causal and time variant 19. Determine the frequency of oscillation for a UJT relaxation oscillator where R = 50kΩ, C = 0.1 pF and η = 0.6. A. 18 H B. 180 Hz C. 218 Hz D. 82 Hz 20. Given x = A'BC(A+D)'. Determine the output of the circuit x if A = 0, B = 1, C = 1, and D = 0. A. 0 B. 1 C. 2 D. NAN 21. An ammeter has a full-scale deflection current of 100 mA. If the same ammeter is used to measure a full-scale current of 1.0 A, what is the value of the shunt resistor in ohms if the voltage across the meter is 9.0 volts? A. 1 B. 900 C. 9 D. 10 22. A silicon diode has a maximum allowable junction temperature of 150^o^C. Find the maximum allowable power dissipation art 25^o^C ambient temperature if the diodes thermal resistance is 0.4^o^C/mW. A. 313 mW B. 600 mW C. 117 mW D. 238 mW 23. In power supplies, circuits that are employed in separating the ac and dc components and bypass the ac components around the load, or prevent their generation are called A. diode circuits C. series capacitors B. filters D. limiters 24. Determine the odd component of the signal, x(t) = cos t + sin t A. sin t B. 2sin t C. cos t D. 2cos t 25. The circuit shown below is a small sine wave signal with average zero and transistor ß. Find the value of R(E) to establish a dc emitter current of about 0.5 mA.  A. 28.57 kΩ B. 57.04 kΩ C. 114.08 kΩ D. 228.16 kΩ 26. If the current through a 10-mH inductor increases from zero to 2 A, how much energy is stored in the inductor? A. 40 mJ B. 10 mJ C. C. 20 mJ \* D. D. 5 mJ 27. An amplifier has a midband power gain of 24, 500. What is the value of the power gain in dB for the circuit? A. 87.78 dB B. 43.9 dB \* C. 4.39 dB D. none of the above 28. **The output voltage of a DC power supply decreases when current is drawn from it because:** 29. A relaxation oscillator is one which E. Has two stable states F. Produces non-sinusoidal output G. relaxes indefinitely H. oscillates continuously 30. If Barkhausen criterion is not fulfilled by an oscillator circuit, it will I. Stop oscillating J. produce damped waves continuously K. Become an amplifier L. produce high frequency whistles 31. A system has a block G~1~(s) which has input x(s) and output y~1~(s). This output is fed as input to a second block G~2~(s) which has output y~2~(s). For this system, G~1~(2) = [\$\\frac{s\^{- 1}}{1 + 2s + s\^{- 2}}\$]{.math.inline}. G~2~(s) for the given system to be invertible is given by \_\_\_\_\_ A. [\$\\frac{s}{1 + 2s + s\^{2}}\$]{.math.inline} B. B. [\$\\frac{1 + 2s + s\^{2}}{s}\$]{.math.inline} C. C. [\$\\frac{1}{1 + 2s + s\^{2}}\$]{.math.inline} D. D. [1 + 2*s* + *s*^2^]{.math.inline} 32. What is the Fourier inverse of [\$H\\left( f \\right) = \\frac{j3\\pi f}{1 + j\\pi f}\$]{.math.inline}? M. N. O. P. 33. The z transform of (n+1)^2^ Q. [\$\\frac{z\^{2}(z + 1)}{{(z - 1)}\^{3}}\$]{.math.inline} R. [\$\\frac{(2z + 1)}{{(z - 1)}\^{3}}\$]{.math.inline} S. [\$\\frac{(2 + z)}{{(z - 1)}\^{2}}\$]{.math.inline} T. [\$\\frac{(3z + 2)}{z - 1}\$]{.math.inline} 34. An alternating voltage given by v = 100 sin 240t volts is applied across a coil of resistance 32 Ω and inductance 100 mH. Determine the circuit impedance. A. 40 ohms B. 50 ohms C. 20 ohms D. 30 ohms 35. Given I~D~ = 4 mA at V~GS~=-2 V, determine I~DSS~ if V~P~=-5 V. 36. Suppose a 1-kΩ resistor will dissipate 1.05 W, and you have many 1-W resistors of all common values. If there's room for 20-percent resistance error, the cheapest solution is to use: 37. The primary reason for making the coil span of a dc armature winding equal to a pole pitch is to: A. obtain a coil span of 180 degrees (electrical) B. ensure the addition of emfs of consecutive turns C. distribute the winding uniformly under different poles D. obtain a full-pitch winding 38. An impedance draws a current i = 10 cos (ωt -- 30°) from a voltage, v = 220 sin (ωt + 30°). What is the impedance? A. 15.6 -- j15.6 B. 19.1 -- j11.1 C. 15.6 + j15.6 D. 11.1 + j19.1 39. Calculate the potential difference between x and y. A diagram of a circuit Description automatically generated A. 4.275 V B. -4.275 V C. 4.527 V D. -4.527 V 40. **If two waves have the same frequency and the same phase, the composite wave:** 41. Calculate the efficiency of a class B amplifier for a supply voltage of VCC=24 V with peak output voltages of VL(p) = 22V. A. 70% B. 74% C. 72% D. 76% 42. For a silicon diode, calculate the current at room temperature if the forward voltage, V~F~ = 0.3 V and the reverse saturation current I~S~ = 100 nA. A. 32.8 µA B. 32.8 mA C. 10.8 µA D. 10.8 mA 43. Depletion region is an area in a semiconductor device where there is no charge carriers exist. This will be always near the junction of n-type and p-type materials. What causes this junction to be depleted by charge carriers? A. Due to recombination of holes and electrons at the junction B. Due to cancellation of positively charged protons and negatively charged electrons C. Due to annihilation of charge carriers D. Due to the combination of positively charged holes and negatively charged electrons 44. Find R~eq~.  U. 29.2 Ω V. 14.4 Ω W. 24.5 Ω X. 2.4 Ω 45. Design this amplifier for a voltage gain of 8 and indicate the required value of resistor RD. A. R~D~ = 9 kΩ B. R~D~ = 10 kΩ C. R~D~ = 3.1 kΩ D. R~D~ =2.7 kΩ 46. A power gain of 44 dB is equivalent to an output/input power ratio of: 47. A linear time-invariant system, initially at rest, when subjected to a unit step input at t = 0, gives a response y(t) = te^-t^ for t ≥ 0. The transfer function of the system is A. [\$\\frac{1}{s\^{2}}\$]{.math.inline} B. [\$\\frac{1}{{(s + 1)}\^{2}}\$]{.math.inline} C. [\$\\frac{s}{{(s + 1)}\^{2}}\$]{.math.inline} D. [\$\\frac{1}{{s(s + 1)}\^{2}}\$]{.math.inline} 48. Which of the following distinguishes the SCR from the SCS? A. The SCS has a fourth terminal, called the anode gate. B. The SCS driven into cutoff using entirely different methods. C. The SCS has less means of being forced into its forward conducting state. D. All of the above. 49. The primary difference between the diac and the SCS is the fact that the \_\_\_\_\_\_\_\_\_. A. Diac has a higher maximum power dissipation rating B. SCS is capable conducting in only one direction C. Diac is no longer used in any practical application D. SCS requires the use of a snubber 50. For the closed-loop system shown, the transfer function [\$\\frac{E(s)}{R(s)}\$]{.math.inline} is A diagram of a block diagram Description automatically generated A. [\$\\frac{G}{1 + GH}\$]{.math.inline} C. [\$\\frac{G}{1 + G}\$]{.math.inline} B. [\$\\frac{1}{1 + GH}\$]{.math.inline} D. [\$\\frac{\\text{GH}}{1 + GH}\$]{.math.inline} 51. Determine the discrete-time signal: x(n) for n ≥ 0 and x(n) = 0 for n \< 0 A. Unit ramp sequence B. Unit impulse sequence C. exponential sequence D. unit step sequence 52. The Fourier series coefficient of time domain signa x(t) is [*x*\[*k*\] = *jδ*\[*k*−1\] − *jδ*\[*k*+1+*δ*\[*k*+3\]+*δ*\[*k*−3\]\]]{.math.inline}, the fundamental frequency of the signal is [*ω* = 2*π*]{.math.inline}. The signal is A. 2(cos 3πt - sin πt) B. -2(cos 3πt - sin πt) C. 2(cos 6πt - sin 2πt) D. -22(cos 6πt - sin 2πt) 53. A transformer coupled class A amplifier turns ratio is 4.5:1 and a load resistance of 30 Ω. What is the approximately the value of the effective AC load resistance seen by the collector of the transistor? A. 400 Ω C. 600 Ω B. 500 Ω D. 700 Ω 54. The unique model of a system is A. Block diagrams B. signal flow graphs C. State variables D. transfer function 55. The operating point is generally located \_\_\_\_\_\_\_\_\_\_\_\_\_ of dc load line in class A operation. A. At the middle C. at cut-off point B. At saturation point D. at end point 56. Which of the following systems is linear? A. y(t) = sin(x(t)) B. y(t) = log(x(t)) C. y(t) = cos(x(t)) D. y(t) = dx(t)/dt 57. The period of the signal x(t) = 10 sin 5t - 4 A. 24π/35 B. 4π/35 C. 2π D. π 58. To turn off the SCR, which of the following is done? A. Reduce gate voltage to zero C. reduce anode voltage to zero B. reverse bias the gate D. reduce cathode voltage to zero 59. A series circuit dissipates a total of 56.25 mW of power with a current of 3.75 mA. If R~2~ dissipates 21.09 mW of power, what is the value of R~1~? A. 2.5 kΩ B. 2 kΩ C. 1 kΩ D. 1.5 kΩ 60. Suppose a resistor with conductance 0.0044 S, a capacitor with susceptance 0.035 S, and a coil with susceptance -0.011 S are all connected in parallel. What is the complex admittance? A. -0.011 + j0.035 B. 0.035 -- j0.011 C. 0.0044 + j0.024 D. 0.0044 + j0.046 61. The inverse Laplace transform of the F(s) =. [\$\\frac{e\^{- 3s}}{{s(s}\^{2} + 3s + 9)}\$]{.math.inline} A. [{0.5+0.5*e*^ − 2(*t*+3)^−*e*^ − (*t*+3)^}*u*(*t*+3)]{.math.inline} B. [{0.5+0.5*e*^ − 2(*t*+3)^−*e*^ − (*t*+3)^}*u*(*t*−3)]{.math.inline} C. [{0.5−0.5*e*^ − 2(*t*+3)^−*e*^ − (*t*+3)^}*u*(*t*+3)]{.math.inline} D. [{0.5−0.5*e*^ − 2(*t*+3)^+*e*^ − (*t*+3)^}*u*(*t*−3)]{.math.inline} 62. Determine the potential difference if it takes 300 mJ of energy to move a charge of 67 μC. A. 44.7 kV B. 37.3 kV C. 3.73 kV D. 4.47 kV 63. A multiplexer is described by its size through \_\_\_\_\_, where n -- number of bits. A. 2^n^ x m C. n x 2^n^ B. 1 x 2^n^ D. 2^n^ x 1 64. An RL high-pass filter consists of a 470-Ω resistor and a 600 mH coil. The output is taken across the coil. The circuit\'s critical frequency is A. 125 Hz B. 1,250 Hz C. 564 Hz D. 5,644 Hz 65. Negative feedback in an amplifier: A. Causes oscillation C. Increases sensitivity B. Reduces the gain D. Is used in an Armstrong oscillator 66. In the figure shown, find the value of R to eliminate output offset.  A. 20.5 kΩ C. 41 kΩ B. 4.1 kΩ D. 20 MΩ 67. Determine the natural response of the system: Difference equation is y(n) -- y(n-1) -- 2y(n -- 2) = x (n) and y(-1) = 1; y(-2) = 0. A. [\$y\_{h}\\left( n \\right) = \\frac{4}{3}{(1)}\^{n} - \\frac{1}{3}{( - 1)}\^{n}\$]{.math.inline} B. [\$y\_{h}\\left( n \\right) = \\frac{4}{3}{( - 1)}\^{n} - \\frac{1}{3}{( - 1)}\^{n}\$]{.math.inline} C. [\$y\_{h}\\left( n \\right) = \\frac{4}{3}{(2)}\^{n} - \\frac{1}{3}{( - 1)}\^{n}\$]{.math.inline} D. [\$y\_{h}\\left( n \\right) = \\frac{4}{3}{(2)}\^{n} - \\frac{1}{3}{(2)}\^{n}\$]{.math.inline} 68. Which of the following is a serial-access medium? A. Computer memory B. Magnetic tape C. A hard drive \\ D. CD-ROM 69. If the stage gain is 20 without feedback and 12 with negative feedback, then what is the feedback factor? A. 0.033 B. 3/5 C. 5/3 D. 1/5 70. Determine the temperature coefficient of a 5-V Zener diode (rated 25°C value) if the nominal voltage drops to 4.8 V at a temperature of 100°C. 71. Find R-value from the below circuit A diagram of a circuit Description automatically generated A. 17.5 Ω B. 17.2 Ω C. 17.4 Ω D. 17.8 Ω 72. Which of the following is correct about photo diode electronic devices? A. P-N junction is connected in reverse bias B. Electron-hole pairs are generated by impurity injection in depletion layer C. It is photovoltaic cell D. No external voltage is applied 73. The transistor in the circuit below is biased at a dc collector current of 0.5 mA. What is the voltage gain?  A. -1 B. -10 C. -100 D. -1000 74. An amplifier rated at 72 W output is connected to an 8-Ω speaker, what is the input voltage rated output if amplifier voltage gain is 40 dB. Y. 100 V Z. 1.2 V A. 160 mV B. D. 240 mV 75. The primary cause of linear distortion in amplifiers is C. Change of gain with frequency D. Unequal phase shift in component frequencies E. Reactances associated with the circuit and active amplifying element F. Inherent limitations of the active devices 76. The forward bias applied to a PN-junction diode is increased from zero to higher values. Rapid increase in the current flow for a relatively small increase in voltage occurs G. immediately H. only after the forward bias exceeds the potential barrier I. when the flow of minority carriers is sufficient to cause an avalanche breakdown J. when the depletion area becomes larger then the space-charge area 77. In a half-wave rectifier, the peak value of the ac voltage across the secondary of the transformer is [\$20\\sqrt{2}\$]{.math.inline} V. If no filter circuit is used, the maximum dc voltage across the load will be K. 28.28 V L. 14.14 V M. 20 V N. 9 V 78. Determine the input impedance at ω = 10 rad/s. Timeline Description automatically generated O. 149.52 -- j195 Ω P. 124.02 + j105 Ω Q. 87.23 -- j96 Ω R. 190 + j67 Ω 79. When determining the common-emitter current gain by making small changes in direct currents, the collector voltage is held constant so that S. The output resistance is high T. The transistor will not burn out U. The change in emitter current will be due to a change in collector current V. The change in collector current will be due to a change in base current 80. The output of a logic gate is 1 when all the input are at logic 0 as shown below:  A screenshot of a cell phone Description automatically generated The gate is either. W. A NAND or an XOR X. an AND or an XOR Y. An OR or an XNOR Z. a NOR or an XNOR 81. Non-volatile memory refers to \_\_\_\_\_\_\_\_\_\_\ a. The memory whose lost data is retained again when power to the memory circuit is removed/applied\ b. The memory which loses data when power to the memory circuit is removed\ c. The memory which loses data when power to the memory circuit is applied\ d. The memory whose loosed data is achieved again when power to the memory circuit is applied 82. Calculate the output voltage using the circuit below for resistor components of value R~f~ = 470 kΩ, R~1~ = 4.3 kΩ, R~2~ = 33 kΩ and R~3~ = 33 kΩ for an input voltage of 80 μV.  a. -1.25 V b. -3.05 V c. 2.42 V d. 1.78 V 83. The turn-off time of thyristor is 30 µs at 50°C. Its turn-off time at 100°C is 84. In an R-L circuit connected to an alternating sinusoidal voltage, size of transient current primarily depends on: A. the instant in the voltage cycle at which circuit is closed B. the peak value of steady-state current C. the circuit impedance D. the voltage frequency 85. A voltage regulator with a no-load output dc voltage of 12 V is connected to a load with a resistance of 10 ohms. If the load resistance decreases to 7.5 ohms, the load voltage will decrease to 10.9 V. The load current will be \_\_\_\_\_\_\_\_ and the percent load regulation is \_\_\_\_\_\_\_\_. 86. What is the design value for Rf? A diagram of a circuit Description automatically generated A. 60 Ω B. 282 kΩ C. 78.3 Ω D. 180 kΩ 87. Determine what maximum dissipation will be allowed for a 90-W silicon transistor (rated 25^O^C) if derating is required above 25^O^C by a derating factor of 0.4 W/^O^C at a case temperature of 145^O^C. A. 30 W B. 36 W C. 48 W D. 42 W \* 88. A Darlington transistor has a Beta of 8000. If R~E~ = 1 kohm and R~L~ = 100 ohm, the input impedance of the base is closest to A. 8 kohm \* B. 800 kohm C. 80 kohm D. 8 Mohm 89. Calculate the voltage gain for this circuit.  E. -137.25\* F. B. -8.4 G. -7.91 H. D. -16.34 90. The maximum collector current (I~CSAT~)for this circuit is \_\_\_\_\_\_\_\_. a. b. c. d. 91. An 8-stage D/A converter has a reference voltage of +12V. What is the resolution of the converter? I. 1.5 V J. 666.67 mV K. 46.875 mV \* L. 47 mV 92. What are the two methods that are commonly used to return an SCR to its conducting state? M. Anode current interruption and forced commutation \* N. Current holding and forced commutation O. Anode current interruption and current holding P. Forced commutation and current dropout 93. Find the current i. A diagram of a circuit Description automatically generated Q. 7.2 A R. 10.5 A S. C. 8.12 A T. D. 12.46 A \* 94. Determine the gain of this circuit.  U. 10 V. B. -10 W. 11 \* X. 1.1 95. A capacitor in an RC circuit with R = 2Ω and C = 4F is being charged. The time required for a capacitor voltage to reach 63.2 % of its steady-state value is Y. 2 s Z. 4 s A. 8 s \* B. 16 s 96. What maximum power can a silicon transistor (T~Jmax~ = 200°C) dissipate into free air at an ambient temperature of 80°C? A. 3 W \* B. 1 W C. 2 W D. 5 W 97. Ferromagnetic coil cores are not generally good for use in RF oscillators because: A. The inductances are too large B. It's hard to vary the inductance of such a coil C. Such coils are too bulky D. Air-core coils have better thermal stability \* 98. An electric charge produces a total electric field of 6 Coulombs, what is the electric flux density in an area of one square meter (1m^2^). A. 1 C/m^2^ B. 4 C/m^2^ C. 2 C/m^2^ D. 6 C/m^2^ \* 99. A coil L~1~ produces 80 µWb of magnetic flux. Of this total flux, 60 µWb are linked with L~2~. Find the coefficient of coupling between L~1~ and L~2~. A. 1.33 B. 4.8 X 10\^-9 C. 0.75 \* D. 0.48 100. Two current sources deliver current to a common load. The first source delivers a current whose equation is 25 sin 100πt amperes while the second delivers a current whose equation is 15 cos 100πt amperes. What is the ms values of the current in the load? 101. **A series connected circuit consists of 3 loads and consume a total power of 50 Watts. It was reconfigured such that 2 are in parallel and the other load is in series with a combination. What is the applied expected powers to be consumed them?**