ELECS COMBI

48. The state of clocked JK flip-flop when Q=0. J=1 and K = 1 is a. high b. low c. 0 d. No change

A

21. The tester is essentially a high-range resistance meter with a built-in direct-current generator. a. Viscometers b. Curve Tracers c. Pyrometers d. Megger

D

35. The oscillating frequency of the quartz crystal can he varied slightly by: a. Changing the bias on the transistor b. Changing the voltage across each one. c. Reversing the power supply polarity d. Placing a small variable capacitor across the crystal.

D

15. If the capacitor has a negative temperature coefficient: a. Its value decreases as the temperature rises. b. Its value increases as the temperature rises. c. Its value does not chance with temperature. d. It must be connected with the correct polarity

A

15. The package of the resistor is rated at 56 Ω plus or minus 10 percent. You test them with an ohmmeter. Which of the following values indicate a reject? a. 50.0 Ω b. 53.0 Ω c. 59.7 Ω d. 61.1 Ω

A

22. A hot-wire ammeter: a. Can measure ac as well as dc b. Can indicate very low voltages c. Measure electrical energy d. Works only when current flows in one direction

A

22. It is used to displays the phase of the colors in color TV a. Vectorscope b. Network analyzer c. Spectrum analyser d. Sweep generator

A

24. A device that can characterize active devices such as transistors and amplifiers using S-parameters as long as they are operating in their linear mode of operation. a. Vector Network analyzer b. Spectrum analyzer c. Vectorscope d. Sweep generator

A

24. Often used to characterize two-port networks such as amplifiers and filters. but they can be used on networks with an arbitrary number of ports. a. Vector Network analyzer b. Spectrum analyzer c. Vectorscope d. Sweep generator

A

40. Drain current in the constant-current region decreases when a. the gate-to-source bias voltage decreases b. the gate-to-source bias voltage increases c. the drain-to-source voltage increases d. the drain-to-source voltage decreases

B

42. A logic gate which produces an output which is false only if all its inputs are true a. NOR b. NAND c. OR d. AND

B

44. The major advantage of Silicon-on-Insulator are the following except: a. Lower diffusion capacitance b. Higher diffusion capacitance c. Lower dynamic power consumption d. Nominals threshold voltage must be very high

B

45. Convert 111101.011012 to octal a. 75.238 b. 75.328 c. 76.328 d. 75.228

B

46. Convert BA2.23C16 to binary. a. 101110100010.00110011112 b. 101110100010.00100011112 c. 101110100110.00100011112 d. 101111100010.00100011112

B

48. The only way to stop an SCR that is conducting is by a. breakover b. low-current drop out c. reverse-bias triggering a positive trigger d. a positive trigger

B

5. The magnetism of ferromagnetic materials such as iron has its origin in the intrinsic magnetic moment of electrons that is associated with their a. Orbital angular momentum. b. Spin angular momentum. c. Electric charge. d. Being magnetically soft.

B

50. One or the other input can be true for the output to be false. a. AND b. NOR c. OR d. XNOR

B

8. In the circuit of Fig. 2. find v2 and i¬2. Figure 2 a. v2 = -4V and i2 = -0.4A b. v2 = -5V and i2 = -0.5A c. v2 = -6V and i2 = -0.6A d. v2 = -7V and i2 = -0.7A

B

16. As the number of turns in a coil increases. the reactance: a. Increases b. Decrease c. Stay the same d. Is stored on the core material

A

20. In a household circuit. the 234V power has a. One phase b. Two phases c. Three phases d. Four phases

C

39. An oscillator might fail to start for any of the following reasons except: a. Low power supply voltage b. Low stage gain c. In-phase feedback d. Very low output impedance

C

4. Hysteresis refers to the ______ between flux density of the material and the magnetizing force applied. a. Ratio b. Equality c. Lagging effect d. Leading effect

C

1. Electric field lines start a. At positive charges or at infinity. b. At negative charges or infinity. c. At infinity and end at positive charges. d. Midway between positive charges and negative charges.

A

10. The resistance of a certain wire is 20Ω. Another wire of the same material and at the same temperature has a diameter one-third as great and a length twice as great. Find the resistance of the second wire. a. 360 Ω b. 180 Ω c. 40 Ω d. 240 Ω

A

26. A silicon sample at room temperature has an intrinsic carrier concentration of ni = 5×109 cm-3. It is doped with ND = 6.1×1016 arsenic atoms/cm3 and NA = 6×1012 boron atoms/cm3. The electron mobility is measured as µn = 1600 cm2/V·s and the hole mobility is µp = 480 cm2/V·s. What is the hole concentration? a. p =4.1x102 /cm3 b. p =6x1012 /cm3 c. p =6.1x1016 /cm3 d. p =2.5x1019 /cm3

A

30. The principal disadvantage of the voltage multiplier a. Poor regulation b. Insufficient rectification c. Excessive current d. Excessive voltage

A

34. If the load impedance for the an oscillator is too high: a. It's not a cause for worry. it can't be too high b. The frequency might drift c. The power output might be reduce d. The oscillator might file to start

A

34. The ac load line differs from the dc load line because a. The effective ac collector resistance is less than the dc collector resistance. b. The effective ac collector resistance is less than the ac collector resistance. c. The effective dc collector resistance is less than the dc collector resistance. d. The effective ac collector resistance is greater than the dc collector resistance.

A

40. A CS amplifier has a load resistance of 10 kΩ and RD = 820 Ω. If g¬m = 5 mS and Vin = 500 mV. the output signal voltage is a. 1.89 V b. 2.05 V c. 25 V d. 0.5 V

A

41. A universal gate is a a. NOR gate b. OR gate c. AND gate d. NOT gate

A

41. Drain current in the constant-current region increases when a. the gate-to-source bias voltage decreases b. the gate-to-source bias voltage increases c. the drain-to-source voltage increases d. the drain-to-source voltage decreases

A

44. The state of clocked JK flip-flop when Q=1 J=1 and K = 1 is a. Toggle b. Reset c. Set d. Not allowed

A

50. An SCR differs from the 4-layer diode because a. it has a gate terminal b. it is not a thyristor c. it does not have four layers d. it cannot be turned on and off

A

6. The magnetic field of a magnetized iron bar when strongly heated a. Becomes weaker b. Becomes stronger c. Reverses in direction d. is unchanged

A

6. When two parallel current-carrying wires have currents in the same direction the wires a. Attract one another. b. Repel one another. c. Exert no forces on one another. d. Exert equal and opposite repulsive forces on one another perpendicular to the plane of the wires.

A

9. Obtain the conductance and susceptance corresponding to a voltage V = 85.0 2050 V and a resulting current I = 41.2 141.00 A. a. 0.471S 0.117S (capacitive) b. 0.471S 0.117S (inductive) c. -0.471S -0.117S (capacitive) d. -0.471S -0.117S (inductive)

A

1. The force between two magnetic poles is _____ their poles strength. a. equal to b. directly proportional to c. inversely proportional to d. directly proportional to the square root of

B

11. In the circuit of Fig 3. v1 = 10V and v2 = 5sin2000t. Find i. Fig. 3 a. i = 1 - 0.35sin(2000t + 450 ) b. i = 1 - 0.35sin(2000t - 450 ) c. i = 1 + 0.35sin(2000t - 450 ) d. i = 1 + 0.35sin(2000t + 450 )

B

12. A certain passive network has equivalent impedance Z = 3+4 Ω and an applied voltage v=42.5cos(1000t + 300) V. Determine the power factor (pf). a. pf = 0.6 lagging b. pf = 0.6 leading c. pf = 0.7 lagging d. pf = 0.7 leading

B

12. Find the current I in the circuit shown. a. 0.234 A b. 0.334 A c. 0.394 A d. 0.424 A

B

14. Find the power factor of a fully loaded 5-hp induction motor that operates at 85 percent efficiency while drawing 15 A from a 480-V line. a. 0.678 lagging b. 0.609 lagging c. 0.645 lagging d. 0.589 lagging

B

16. A phase difference of 180 degrees in the circular model: a. ¼ revolution b. ½ revolution c. A full revolution d. Two full revolution

B

18. If the ratio of Xc / R is 1. the phase angle is: a. 0 degrees b. -45 degrees c. -90 degrees d. 45 degrees

B

25. A small-signal amplifier a. always has an output signal in the mV range b. uses only a small portion of its load line c. goes into saturation once on each input cycle d. is always a common-emitter amplifier

B

28. A p-channel MOSFET operating in the enhancement mode is characterized by VT = - 3V and IDQ= -8 mA when VGSQ = -4.5 V. Find VGSQ if IDQ = -16 mA. a. VGSQ =- 0.80 V b. VGSQ = - 0.88 V c. VGSQ = - 0.94 V d. VGSQ = - 0.78 V

B

29. In a p-channel FET the charge carriers are ..... a. electrons b. holes c. both holes and electrons d. ions

B

3. The magnetic flux of 2000 lines is how many Maxwells? a. 1000 b. 2000 c. 4000 d. 8000

B

33. How can a class-C amplifier be made linear? a. By reducing the bias b. A class-C amplifier cannot be made linear c. By increasing the drive d. By using two transistor in push-pull

B

33. The gate of a JFET has: a. Forward bias b. High impedance c. Low reverse resistance d. Low avalanche voltage

B

35. It is a method of stabilizing the voltage gain. a. Darlington pair b. Swamping c. Differential mode d. Common mode

B

38. A class-A circuit would not work well as: a. A stereo hi-fi amplifier b. A television transmitter PA c. A low-level microphone preamplifier d. The first stage in the radio receiver

B

38. In nMOS transistor which operation is for saturation mode? a. Vgs > Vt Vgs >Vgd>Vt and 0<Vds<Vgs-Vt b. Vgs > Vt Vgs <Vgd and Vds>Vgs-Vt c. Vgs >Vt Vgd = Vgs and Vds = 0 d. Vgs = 0 and Vgd is high

B

10. A 100-kVA transformer is at 80 percent of rated load at power factor 0.85 lagging. How many kVA in additional load at 0.60 lagging power factor will bring the transformer to full rated load? a. 21.8 kVA b. 22.2 kVA c. 21.2 kVA d. 22.4 kVA

C

11. A wire 50 m in length and 2 mm2 in cross section has a resistance of 0.56 Ω. A 100-m length of wire of the same material has a resistance of 2 Ω at the same temperature. Find the diameter of this wire. a. 1.8 mm b. 1.4 mm c. 1.2 mm d. 1.0 mm

C

13. A three-phase. three-wire. ABC system with a balanced load has effective line voltage 200V and (maximum) line current IA = 13.61 600 A. Obtain the total power. a. 2807 W b. 2708 W c. 2887 W d. 2788 W

C

17. Inductive susceptance is a. Equal to capacitive reactance b. The measure of the opposition a coil offers to ac. c. Negative imaginary d. The reciprocal of inductance

C

2. The electric flux through a surface of fixed area is maximum when the surface is a. Parallel to the electric field. b. Antiparallel to the electric field. c. Perpendicular to the electric field. d. At an angle of 45◦ to the electric field.

C

20. In an RLC series circuit the circuit frequency is below the resonant frequency then a. Z = R b. XC = XL c. XC > XL d. XC < XL

C

23. It can also be used to locate the source of a field. and to measure the performance of radiofrequency shielding. a. Oscilloscope b. Logic analyzer c. RF Meter d. Spectrum analyzer

C

23. The meter movement in an illumination meter measures: a. Voltage b. Power c. Current d. Energy

C

25. A Zener diode has the specifications VZ = 5.2 V and PD max = 260 mW. Assume RZ = 0. Find the maximum allowable current iZ when the Zener diode is acting as a regulator a. iZ = 30mA b. iZ = 45mA c. iZ = 50mA d. iZ = 60mA

C

26. The junction FET the control electrode is usually the: a. Source b. Emitter c. Gate d. Drain

C

27. In the circuit below. the Zener diode has a breakdown voltage VZT = 8.0 V and a measurement has shown that VZ = 8.6 V when IZ = 30 mA. What is the value of Vout when RL becomes infinitely large? a. Vout = 0 V b. Vout = 8.2 V c. Vout¬ = 8.8 V d. Vout = 8.4 V

C

28. A silicon sample at room temperature has an intrinsic carrier concentration of ni = 5×109 cm-3. It is doped with ND = 6.1×1016 arsenic atoms/cm3 and NA = 6×1012 boron atoms/cm3. The electron mobility is measured as µn = 1600 cm2/V·s and the hole mobility is µp = 480 cm2/V·s. What is the hole concentration? a. p =6x1012 /cm3 b. p =2.5x1019 /cm3 c. p =4.1x102 /cm3 d. p =6.1x1016 /cm3

C

30. In a source follower. which of the electrodes of FET receives the input signal? a. None of them b. The source c. The gate d. The drain

C

31. The ac load line differs from the dc load line because a. The effective dc collector resistance is less than the dc collector resistance. b. The effective ac collector resistance is less than the ac collector resistance. c. The effective ac collector resistance is less than the dc collector resistance. d. The effective ac collector resistance is greater than the dc collector resistance.

C

32. In a P-channel JFET: a. The drain of is forward-biased b. The gate-source junction is forward biased c. The drain is negative relative to the source d. The gate must be at the dc ground.

C

36. The features of CASCODE amplifier are a. Reduced distortion b. Small input impedance c. Large output impedance d. Larger bandwidth

C

37. An IC constructed entirely on a single silicon chip. a. Thin-film b. Thick-film c. Monolithic d. Hybrid

C

37. If the dc emitter current in a certain transistor amplifier is 3 rnA. the approximate value of r'e is a. 3 kΩ b. 3 Ω c. 8.33 Ω d. 0.33 kΩ

C

4. If an electron moves from right to left across this page and suddenly is subjected to a magnetic field directed into the page what is the direction of the magnetic force on the electron? a. Into the page b. Out of the page c. From the bottom to the top of the page d. From the top to the bottom of the page

C

42. A MOSFET differs from a JFET mainly because a. of the power rating b. the MOSFET has two gates c. the JFET has a pn junction d. MOSFETs do not have a physical channel

C

45. A logic circuit has an output 0 when the input is 1. and vice versa. a. NOR gate b. OR gate c. NOT gate d. XOR gate

C

49. ____________ is called bistable multivibrator circuit a. an NAND gate b. an XOR gate c. a flip-flop d. a clock

C

5. The permeability of permalloy is a. Slightly less than permeability of air b. Slightly greater than permeability of air c. Very much greater than permeability of air d. Equal to the permeability of air

C

7. The impedance of R-C series circuit is 100Ω. If circuit current leads the applied voltage by 60o. the capacitive reactance is____ a. 50Ω b. 70.7Ω c. 86.6Ω d. 200Ω

C

8. Power absorbed in a pure inductive circuit is zero because a. Reactive component of the current is zero b. Active component of the current is maximum c. Power factor of the circuit is zero d. Reactive and active components of the current cancel out

C

9. At series resonance the voltage across L or C is a. Equal to the applied voltage b. Less than the applied voltage c. Much more than the applied voltage d. Equal to the voltage across R

C

13. For the circuit shown what load impedance ZL absorbs maximum average power? a. -8.46 2.61o b. -8.92 2.31o c. 8.22 2.44o d. 8.46 2.81o

D

14. A coil is represented by a series combination of L = 50 mH and R = 15 Ω. Calculate the quality factor at 10kHz. a. Q¬coil ¬= 1047 b. Q¬coil ¬= 845 c. Q¬coil ¬= 326 d. Q¬coil ¬= 209

D

17. Each point in the RC plane a. Corresponds to a unique inductance b. Corresponds to a unique capacitance c. Corresponds to a unique combination of resistance and capacitance d. Corresponds to a unique combination of resistance and reactance

D

18. The low power factor of the circuit means that it will a. draw more active power b. less line current c. cause less voltage drop in the line d. draw more reactive power

D

19. As the capacitor plate area increases all things being equal a. the capacitance decreases b. the capacitance do not change c. the voltage-handling ability increases d. the capacitance increases

D

19. Inductive susceptance is a measured in a. Ohms b. Henrys c. Farads d. Siemens

D

2. Hysteresis refers to the ______ between flux density of the material and the magnetizing force applied. a. Leading effect b. Ratio c. Equality d. Lagging effect

D

21. A ammeter shunt is useful because a. It prevents overheating of the meter b. It makes a meter more physically rugged c. It allows for measurements of a wide range of current d. It increases meter sensitivity

D

27. Equivalent circuit model commonly used in small signal analysis at high frequencies. a. ideal model b. Hybrid-Pi or Giacoletto c. H parameters d. Ebers-Moll

D

29. In an N-channel JFET. the pinchoff occurs when the gate bias is: a. Slight positive b. Zero c. Slight negative d. Very negative

D

3. The head of a nail is attracted to the north pole of a magnet and repelled by the magnet's south pole. a. The nail is aluminum. b. The nail is copper. c. The nail is initially not magnetized. d. The nail is magnetized.

D

31. The input impedance of a MOSFET: a. Is lower than the JFET b. Is lower than the bipolar transistor c. Is between that of the bipolar transistor and a JFET d. Is extremely high

D

32. An oscillator might fail to start for any of the following reasons except: a. Low power supply voltage b. Low stage gain c. Very low output impedance d. In-phase feedback

D

36. Each stage of a four-stage amplifier has a voltage gain of 15. The overall voltage gain is a. 15 b. 60 c. 3078 d. 50.625

D

39. Dynamic gates drives multiple-input static CMOS gates are susceptible to a. Hot spots b. Minority carrier injection c. Leakeage d. Back-end coupling

D

43. On combinational circuit design. which of the following NOT cascadeable circuit? a. Pseudo-nMOS b. Complementary Pass Transistor Logic c. Static CMOS d. Dynamic

D

43. The state of asynchronous enable SR latch when both signals are '1' and enable is '1'. a. No change b. Reset c. Set d. Not allowed

D

46. The gigabyte is a unit commonly used to measure of a. Data access time b. Data transfer time c. Data communication accuracy d. Data storage capacity

D

47. For a UJT the intrinsic standoff ratio is a. usually around 1k or so b. equal to 1 c. always greater than 1 d. always less than 1

D

47. The state of SR latch when both signals are '1'. a. No change b. Reset c. Set d. Not allowed

D

49. The PUT is a. Not a thyristor b. Much like the UJT c. Not a four-layer device d. Trigger on and off by the gate-to-anode

D

7. Find Thevenin equivalent of the circuit of Figure 1 seen from terminals AB. Figure 1 a. Vth = 12V . Rth = 15Ω b. Vth = 15V . Rth = 12Ω c. Vth = 12V . Rth = 12Ω d. Vth = 12V . Rth = 17Ω

D