MULTIPLE CHOICE QUESTIS IN ELECTRONICS ENGINEERING
by
RONIE VILLAMOR
Encoded by: VILLAMOR, Mara Mariz M.
1. What is the smallest element of a matter? a. atom
b. molecule c. crystal d. wafer
2. To determine whether a material can support the flow of electricity or not, we need to examine its
a. atomic structure b. physical state c. molecular structure d. chemical composition 3. Approximate diameter of an atom
a. 10^-10 µµm b. 10^-10 µm c. 10^-10 mm d. 10^-10 m
4. Known as the simplest type of atom a. Hydrogen
b. Oxygen c. Helium d. Nitrogen
5. Approximate diameter of a Hydrogen atom a. 1.1 x 10^-10 µµm
b. 1.1 x 10^-10 µm c. 1.1 x 10^-10 mm d. 1.1 x 10^-10 m
6. What is the charge of an electron? a. 1.6022 x 10^-19 C
b. 9.1096 x 10^-19 C c. 1.6022 x 10^-31 C d. 9.1096 x 10^-31 C
7. Protons are about ____ heavier than electrons a. 1,800 times
b. Less than thrice c. Less
8. Approximately, how many electrons that could equal to the mass of a single proton or neutron? a. 1,863 electrons b. 1,683 electrons c. 1,638 electrons d. 1,836 electrons
9. If an element has an atomic number of 12, there are how many protons and electrons?
a. 6 protons and 12 electrons b. 12 protons and 6 electrons c. 12 protons and 12 electrons d. 12 protons and 24 electrons
10. It is composed of a series of energy levels containing the valence electrons a. conduction band
b. forbidden band c. sideband d. valence band
11. Electrons at the conduction band are called a. free electrons
b. valence electrons c. deep state electrons d. shallow state electrons
12. A good conductor has how many valence electrons? a. 1
b. 2 c. 4 d. 8
13. Determine which statement is true?
a. The current carriers in conductors are protons.
b. The current carriers in conductors are valence electrons. c. Valence and inner electrons are the carriers in conductors. d. Valence electrons are not the ones that become free electrons. 14. A material that contains an abundance of free carrier is called
a. Insulator b. Semi-insulator c. Conductor d. Semiconductor
15. From the combined energy-gap diagram, which material has the widest gap between valence band and the conduction band?
a. Conductor b. Semiconductor c. Super conductor d. Insulator
16. A solid, which has no defined crystal structure a. Crystalline
b. Non-crystalline c. Amorphous
d. Non-crystalline or Amorphous
17. Ideally, all atoms have the same number of positively charged protons and negatively charged electrons, and is therefore as
a. Electrically neutral b. Physically stable c. Magnetically aligned d. Technically rigid 18. A positive ion has
a. excess of electrons b. excess of neutrons c. lack of electrons d. lack of protons
19. One Coulomb of charge has how many electrons? a. 6.24 x 10^18 electrons
b. 6.24 x 10^19 electrons c. 62.4 x 10^18 electrons d. 62.4 x 10^19 electrons
20. One ampere is equal to how many electrons per second? a. 1 x 10^18 electrons/sec.
b. 1 x 10^19 electrons/sec. c. 6.25 x 10^18 electrons/sec. d. 6.25 x 10^19 electrons/sec.
21. The greater the diameter of a wire, the ___ is the resistance. a. greater
b. lesser c. harder d. bigger
22. A 100m long wire with a cross-sectional area A=10^-3 m^2 has a resistance of 10 ohms. Determine the resistivity of the wire.
a. 10^-2 ohms-m b. 10^-3 ohms-m c. 10^-4 ohms-m d. 10^-5 ohms-m
23. The science of physical phenomena at very low temperature, approaching absolute zero is called ___.
a. crytanalysis b. cybernetics
c. temperature inversion d. cryogenics
24. A wire has a resistance of 5 ohms at room temperature and a temperature coefficient α =4 x 10^-3 / ºC, calculate the wire resistance at 75 ºC.
a. 8.925 ohms b. 7.925 ohms c. 6.925 ohms d. 6.050 ohms
25. The temperature coefficient of resistance of a certain wire is known to be 0.004/ ºC at zero degree Celsius. What would be the temperature coefficient at room temperature?
a. 0.00018/ºC b. 0.00036/ºC c. 0.00180/ºC d. 0.00360/ºC
26. Find the change in coulombs of dielectric that has a positive charge of 14.5 x 10 to the 18the power protons.
a. 29 x 10 to the 16th Coulombs b. 14.5 x 10 to the 16th Coulombs c. 14.5 x10 to the 18th Coulombs d. 29 x 10 to the 18th Coulombs
27. What is the law whereby the force of attraction and repulsion between poles is inversely proportional to the square of the distance between them?
a. Newton’s first law b. Newton’s second law c. Norton’s law
28. Three charges of +5 C, -6 C and +7 are placed inside a sphere, what is the total charge of the sphere?
a. +5 Coulomb b. -6 Coulomb c. +7 Coulomb d. +6 Coulomb
29. What is true in visualizing electric field lines of force from a charge body? a. Field lines are continuous curve and they never intersect.
b. The spacing between these lines increases as they get far from the charged body.
c. The number of field lines is directly proportional to the magnitude of the electric field.
d. All of the above.
30. Electric lines of force leave and enter the charge surface at what angle? a. 15 º
b. 30 º c. 45 º d. 90 º
31. Electric flux is a/an ________ quantity. a. scalar
b. vector c. absolute d. relative
32. An electric charge produces a total electric field of 6 Coulombs, calculate the electric flux density in an area of one square meter (1m2)
a. 1 C/m^2 b. 2 C/m^2 c. 4 C/m^2 d. 6 C/m^2
33. The absolute permittivity of air or free space. a. 1/36π x 10^-9 F/m
b. 36π x 10^-9 F/m c. 1/36π x10^-19 F/m d. 36π x 10^-19 F/m
34. In 1784, who demonstrated that the force between charges is inversely related to the square of the distance between them?
a. Maxwell b. Gauss c. Tesla d. Coulomb
35. Calculate the electric field intensity 10 cm from a charge Q=5nC. a. 450 N/C
b. 900 N/C
c. 4.5 x 10^3 N/C d. 9.0 x 10^3 N/C
36. Calculate the total electric field at the surface of a sphere of radius r=1cm, and enclosing a net charge of 2µC.
a. 0 (zero) b. 9 x 10^7 N/C c. 1.8 x 10^8 N/C d. Infinite
37. A charged body in free spaces produces 10-V potential at a distance 25 cm away. What will be the potential at 50 cm away?
a. 5.0 Volts b. 7.5 Volts c. 10.0 Volts d. 15.0 Volts
38. Which of the materials below that can be easily magnetized? a. soft magnetic materials
b. hard magnetic materials c. low conductive materials d. high conductive materials
39. Materials with permeability slightly less than that of free space. a. diamagnetic
b. paramagnetic c. ferromagnetic d. antimagnetic
40. The unit of magnetic flux density in SI a. Gauss
b. Weber c. Maxwell d. Tesla
41. 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
42. Calculate the flux density in Gauss (G) having a flux of 12,000 Mx through a perpendicular area of 6 cm. a. 200 G b. 2,000 G c. 7,200 G d. 72,000 G
43. If the distance between the two magnetic poles is halve, the force between them a. decreases two times
b. decreases four times c. increases two times d. increases four times 44. Unit of permeability
a. Henry/meter (H/m) b. Farad/meter (F/m) c. Henry-meter (H-m) d. Farad-meter (F-m) 45. The unit of permittivity
a. Henry/meter (H/m) b. Farad/meter (F/m) c. Henry-meter (H-m) d. Farad-meter (F-m) 46. One Weber is equivalent to
a. 10^8 Maxwells b. 10^6 Maxwells c. 10^4 Maxwells d. 10^2 Maxwells 47. Permeance is analogous to a. Conductance b. Resistance c. Impedance d. Elastance
48. The Oersted (Oe) is the same as a. 1 Gb/cm
b. 1 Gb/m c. 10 Gb/cm d. 10 Gb/m
49. The unit of reluctance a. Gilbert
b. Tesla c. At/Wb d. Gauss
50. Determine the ampere-turns when a 10V battery is connected across a solenoid having 100 turns and a resistance of 5 ohms.
a. 50 At b. 200 At c. 100 At d. 1,000 At
51. If a wire coil has 100 turns and carries 1.3 A of current, calculate the magnetomotive force in Gilbert.
a. 163.3 b. 16.33 c. 1.633 d. 0.1633
52. If two coils are close enough together for their magnetic fields to interact, a change in current in one will induce a corresponding voltage in the other. This condition is known as
a. self-inductance b. mutual inductance c. crossfire inductance d. linked inductance
53. When a conductor is moved through a magnetic field a voltage is always induced. The amount of voltage is always proportional to
a. The diameter of the conductor used b. The length of the conductor
c. The distance of the conductor from the field d. The rate at which the conductor is moved 54. What is meant by back EMF?
a. A voltage that is applied in the reverse direction b. An EMF that is due to the fly wheel effect
c. An EMF that is generated from the back of an electromagnet d. A voltage that opposes the applied EMF
55. In electromagnetism, what law determines the amount of induced voltage? a. Ampere’s law
b. Lenz’ law c. Coulomb’s law d. Faraday’s law
56. The effect that describes the ability of a mechanically stressed ferromagnetic wire to recognize rapid switching of magnetization when subjected to a DC magnetic field
a. Wiegand effect b. Wertheim effect c. Wiedemann effect d. Wall effect
57. _________ is called the magnetic field
a. The force that drives current through a resistor
b. Current flow through space around a permanent magnet c. The force between the plates of charged capacitor
d. A force set up when current flow through a conductor
58. What is the value of a resistor with colors from left: Orange, Blue, Gold and Silver?
a. 34 ohms ± 10% b. 3.6 ohms ± 10% c. 3.4 ohms ± 10% d. 36 ohms ± 10%
59. Resistors with high value usually have lower wattage ratings because of _________.
a. varying current b. lower current c. bigger size d. high current
60. A 33 kilo ohms resistor is connected in series with a parallel combination made up of a 56 kilo ohm resistor and a 7.8 kilo ohm resistor. What is the total combined resistance of these three resistors?
a. 63769 ohms b. 49069 ohms c. 95800 ohms d. 39067 ohms
61. If you need a 1.25 kilo ohms resistance and you only have resistors of 5 kilo ohms, how many of these available resistors you should connect in parallel to get a 1.25kilo ohms value?
a. 2 b. 3 c. 4 d. 5
62. _______ is used to store electrical energy in an electrostatic field? a. A transformer
b. A battery c. A capacitor d. An inductor
63. What factors determine the capacitance of a capacitor?
a. Area of the plates, amount of charge in the plates and the dielectric constant of the material between the plates
b. Area of the plates, voltage on the plates and distance between the plates c. Area of the plates, distance between the plates and the dielectric
constant of the material between the plates
d. Area of the plates, voltage of the plates and the dielectric constant of the material between the plates
64. A parallel plate capacitor has the following values: k=81; d=0.025 inches; A=6 square inches. What is the capacitance of the capacitor?
a. 4.372 picofarad b. 43.72 picofarad c. 4372 picofarad d. 4.372 picofarad
65. If two micro-farad capacitors are connected in series, what will be the total effective capacitance?
a. 0.125 microfarad b. 0.0624 microfarad c. 2.5 microfarad d. 0.50 microfarad
66. A coil of wire wound, with or without a magnetic core designed to have a higher self-inductance than a straight wire
a. Inductor b. Solenoid c. Toroid
d. Inductive relay
67. Two resistors, 10 ohms and 100 ohms are connected in parallel approximately, what is the total resistance?
a. 10 ohms b. 50 ohms c. 90 ohms d. 100 ohms
68. A shunt resistor is used to limit the load current to 0.5 A. If the load resistance is 100 ohms and the original current is 1 amp, what should be the value of the shunt resistance?
a. 25 ohms b. 50 ohms c. 75 ohms d. 100 ohms
69. Two resistors, R1=100 ohms and R2=200 ohms are connected in parallel. If the current through R1 is 1 A, what would be the current on R2?
a. 0.125 A b. 0.25 A c. 0.35 A d. 0.50 A
70. A constant voltage source Vs=60 is delivering power to a series combination of R1=100 ohms, R2=200 ohms and R3=300 ohms. Calculate the voltage drop across R2.
a. 10 V b. 20 V c. 30 V d. 40 V
71. If 12 V are applied to a circuit that consumes 78 W, what is the current flow through the circuit?
a. 6.5 A b. 936 A c. 0.15 A d. 9.36 A
72. The power dissipated by a 10 ohms load resistor with a current rating of 5 amperes is ________ if supplied with a 20 volt dc potential
a. 40 W b. 80 W c. 160 W d. 250 W
73. The power in a circuit consisting of two equal resistors in series is known to be 10 watts. If the two resistors are connected in parallel, what would be the circuit power dissipation?
a. 2.5 watts b. 5 watts c. 20 watts d. 40 watts
74. How many nodes are needed to completely analyze a circuit according to Kirchoff’s current law?
a. Two
b. All nodes in the circuit
c. One less than the total number of nodes in the circuit d. One
75. In a mesh, the algebraic sum of all the voltages and voltage drops is equal to zero a. Superposition theorem
b. Norton’s law c. Kirchoff’s first law d. Kirchoff’s second law
76. Theorem used to simplify complex circuits wherein, the simplified circuit contains an equivalent open circuit resistance and open circuit voltage
a. Norton’s b. Thevenin’s c. Maxwell’s d. Kirchoff’s
77. A certain Thevenin equivalent circuit has parameters Rth=10 ohms and Vth=20V. if this is converted to Norton’s equivalent circuit, Rn and In would be
a. 10 ohms and 2 A b. 10 ohms and 4 A c. 0.10 ohms and 2 A d. 0.10 ohms and 4 A
78. Rn and In of a Norton’s equivalent circuit are known to be 100 ohms and 10 A respectively. If a 400 ohms load is connected, it will have a load current of
a. 1 A b. 2 A c. 3 A d. 4 A
79. In a network, what do we call a reference point chosen such that more branches in a circuit met.
a. node b. junction c. ground d. mesh
80. The return point in a circuit, where all voltage measurements are referred a. node
b. junction c. ground d. loop
81. Three 100 ohms resistors are connected in tee-form (T) network and is set up between a 100 V supply and a load resistor Rl. If maximum power transfer is desired, what should be the resistance of the load resistor Rl?
a. 50 ohms b. 75 ohms c. 125 ohms d. 150 ohms
82. Three resistors, R1=60 ohms, R2=80 ohms and R3=100 ohms are connected in delta. If the network is to be transformed into star, what would be the value of the resistor opposite to R2?
a. 25.0 ohms b. 33.3 ohms c. 45.0 ohms d. 56.7 ohms
83. An alternating voltage of sine-wave form has a maximum voltage of 311 V. what is its value at 225º?
a. 110 V b. 220 V c. -220 V d. -110 V
84. If an alternating voltage has a magnitude of 10 V at 30º, what is its maximum voltage?
a. 20 V b. 30 V c. 40 V d. 50 V
85. What is the frequency of an alternating current, if it reaches 90º within 4.167 ms? a. 20 Hz
b. 30 Hz c. 50 Hz d. 60 Hz
86. At what angle does an alternating voltage of cosine-wave form reaches its negative peak?
a. 45º b. 90º c. 135º d. 180º
87. When comparing rms voltages and average voltages, which of the following statement is true, assuming sine waves?
a. Either the rms voltage or the average voltage might be larger b. The rms voltage is always greater than the average voltage
c. There will always be a very large difference between the rms voltage and the average voltage
d. The average voltage is always greater than the rms 88. What do you mean by root-mean-squared (rms) voltage?
a. It is the average value b. It is the effective value
c. It is the value that causes the same heating effect as a dc-voltage d. B or C
89. In a purely inductive circuit the current a. Leads the voltage by 45º b. Leads the voltage by 90º c. Lags the voltage by 90º d. Lags the voltage by 45º
90. A resistive and a capacitive load of equal magnitude is connected in series, determine the phase difference between the voltage and the current.
a. Current leads the voltage by 45º b. Current lags the voltage by 45º c. Current leads the voltage by 90º d. Current lags the voltage by 90º
91. The reactance of a 25 mH coil at 500 Hz is which of the following? a. 785 ohms
b. 785,000 ohms c. 13 ohms d. 0.0013 ohms
92. A 220-volt, 60 Hz source is driving a series RL circuit. Determine the current in the circuit if R=100 ohms and XL= 100 ohms.
a. 1.10 A(lagging) b. 1.55 A(lagging) c. 2.20 A(lagging) d. 4.40 A(lagging)
93. What will be the current equation in a series RC network if supplied with v=Vmsin120πt source? The circuit has a power factor pf=0.5.
a. i = Imax sin(120πt + 60) b. i = Imax sin(120πt - 60) c. i = Imax sin(120πt + 30) d. i = Imax sin(120πt - 30)
94. What is the power factor (pf) of a series RL circuit having R=50 ohms and XL=20 ohms? a. 0.63 b. 0.71 c. 0.81 d. 0.93
95. What will happen when the power factor of a circuit is increased? a. Reactive power increases
b. Active power increases
c. Both active and reactive powers increases d. Both active and reactive powers decrease
96. A 6-ohms resistor is connected in series with a capacitive reactance of 8 ohms. If the supply voltage is 200 V, what is the circuit current magnitude?
a. 14.28 A b. 20 A c. 25 A d. 33.33 A
97. The apparent power of a series RC network is given to be 4000 W. If R=6 ohms and XC=8 ohms, calculate the true power of the network.
a. 1200 W b. 2400 W c. 3200 W d. 4000 W
98. A series RC circuit has an apparent power of 4000 W. If R=6 ohms and XC=8 ohms, determine the reactive power.
a. 1200 W b. 2400 W c. 3200 W d. 4500 W
99. What is the total impedance of a series circuit consisting of R=6 ohms, XC=8 ohms and XL=16 ohms?
a. 10 ohms b. 14 ohms c. 24.73 ohms d. 30 ohms
100. What is the significance of connecting loads in parallel? a. It makes power consumption less
b. It provides greater efficiency c. It increases the safety factor
101. The name of pure semiconductor material that has equal number of electrons and holes
a. n-type b. pure type c. intrinsic d. p-type
102. Which of the following is an example of a compound semiconductor? a. Gallium Arsenide (GaAs)
b. Gallium Phosphide (GaP) c. Aluminum Arsenide (AlAs) d. All of the above
103. Germanium has an atomic number of 32 and atomic weight of approximately 72 amu. How many electrons, protons and neutrons are there?
a. 32,32,40 b. 32,32,104 c. 40,32,32 d. 40,32,104
104. The atomic weight of a silicon atom is approximately 28 amu. How may electrons, protons and neutrons does the atom consist?
a. 14,42,14 b. 14,14,42 c. 42,14,14 d. 14,14,14
105. A semiconductor that is free from impurities a. intrinsic semiconductor
b. extrinsic semiconductor c. compensated semiconductor d. elemental semiconductor 106. Example of acceptor impurities
a. pentavalent impurities b. trivalent impurities c. tetravalent impurities d. hexavalent impurities
107. Commonly used as donor impurities a. Antimony (Sb)
b. Arsenic (As) c. Phosphorus (P) d. All of the above
108. What do you call a semiconductor that is doped with both donor and acceptor impurities?
a. double doped semiconductor b. compensated semiconductor c. compound semiconductor d. diffused semiconductor
109. Semiconductor whose electron and hole concentrations are equal a. extrinsic semiconductor
b. intrinsic semiconductor c. compensated semiconductor d. doped semiconductor
110. Typically, how much energy is required for a valence electron to move to the conduction band for a doped semiconductor?
a. 0 eV b. 0.05 eV c. 1.0 eV d. 5.0 eV
111. The electrical resistance of a semiconductor material will _______ as the temperature increases
a. increase
b. increase exponentially c. decrease
d. not change
112. At room temperature, in a perfect silicon crystal, the equilibrium concentration of thermally generated electrons in the conduction band is about
a. 1.5 x 10^5 per cubic cm b. 1.5 x 10^10 per cubic cm c. 1.5 x 10^15 per cubic cm d. 1.5 x 10^20 per cubic cm
113. What is the basis in operation of semiconductor photoconductors? a. EHP generation
b. EHP degeneration
c. EHP optical degeneration d. EHP optical generation
114. Typical range of power dissipation for a semiconductor to be considered as “low power” or “small signal”
a. less than 1 watt b. 5< P <10 watts c. 10< P <20 watts d. 20 watts above
115. What is formed when n-type and p-type semiconductors are brought together?
a. pn junction
b. semiconductor junction c. energy band gap d. semiconductor diode
116. PN junction acts as a one way valve for electrons because ______________
a. the circuit in which the diode is used, only attempts to pump electrons in one diode
b. electrons tend to follow the direction of the hole c. there is a little mechanical switch inside a diode
d. when electrons are pump from p to n, free electrons and holes are force apart leaving no way for electrons to cross the junction
117. An external voltage applied to a junction reduces its barrier and aid current to flow through the junction
a. reverse bias b. external bias c. junction bias d. forward bias
118. Unidirectional conduction in two-electrodes in any device other than a diode, such that rectification between the grid and cathode of a triode, or asymmetrical conduction between the collector and base of a transistor is called
a. rectification b. diode action c. dipping d. clamping
119. Depletion region is an area in a semiconductor device where there are 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 the recombination of holes and electrons at the junction
b. Due to the cancellation of positively charge protons and negatively charge electrons
c. Due to the annihilation of charge carriers
d. Due to the combination of positively charge holes and negatively charge electrons
120. A junction diode is said to be forward-biased if a. Anode is supplied more positive than the cathode b. Anode is supplied more negative than the cathode
c. A voltage greater than threshold is applied, with cathode less positive than anode
d. A voltage greater than threshold is applied, with cathode less negative than anode
121. The minimum voltage required before a diode can totally conduct in a forward direction
a. triggering voltage b. breakdown voltage c. saturation voltage d. threshold voltage
122. As the operating temperature of as reverse-biased diode is increase, its leakage or reverse saturation current will
a. increase
b. increase exponentially c. decrease
d. decrease exponentially
123. The breakdown voltage of junction diode will _____ a. increase as operating temperature rises
b. increase exponentially as operating temperature rises c. decrease as operating temperature rises
d. not change as operating temperature rises
124. Calculate the new threshold voltage of a germanium diode when it operates at 100ºC
a. 0.113 V b. 0.188 V c. 0.215 V d. 0.513 V
125. A silicon diode has a reverse saturation current of 50 nA at room temperature. If the operating temperature is raised by 50ºC, what is now the reverse saturation current?
a. 105.56 nA b. 287.73 nA c. 827.89 nA d. 1.66 µA
126. In a semiconductor diode, the total capacitance, that is the capacitance between terminals and electrodes, and the internal voltage variable capacitance of the junction is called
a. diffusion capacitance b. transition capacitance
c. depletion-region capacitance d. diode capacitance
127. What capacitance is significant when the diode is forward biased? a. diffusion capacitance or storage capacitance
b. transition capacitance
c. depletion-region capacitance d. stray capacitance
128. A diode that is especially designed to operate as a voltage-variable capacitor. It utilizes the junction capacitance of a semiconductor diode.
a. varactor b. varicap c. varistor
d. A and B are correct
129. A certain diode has a maximum power dissipation of 500 mW at room temperature and a linear derating factor of 5.0 mW/ºC. How much power the diode can handle if operated at 50ºC?
a. 625 mW b. 505 mW c. 495 mW d. 375 mW
130. A semiconductor device especially fabricated to utilize the avalanche or zener breakdown region. This is normally operated in the reverse-region and its application mostly for voltage reference or regulation.
a. varactor diode b. zener diode c. shockley diode d. schottky barrier diode
131. Refers to a special type of diode which is capable of both amplification and oscillation
a. junction diode b. tunnel diode c. point contact diode d. zener diode
132. A rectifying metal-semiconductor junction a. schottky barrier diode
b. surface barrier diode
c. hot-carrier or hot-electron diode d. All of the above are correct
133. Another name of a three-layer diode. This is also considered as an ac diode
a. shockley diode b. thyrector c. thyristor d. diac
134. When the p-n junction of a semiconductor diode is inserted with intrinsic material, the diode becomes a
a. backward diode b. read diode c. shockley diode d. PiN diode
135. A diode that is especially processed so that its high-current flow takes place when the junction is reversed-biased. It is a variation of a tunnel diode.
a. esaki diode b. read diode c. zener diode d. backward diode
136. Is the combination of the inductance of the leads and electrodes, capacitance of the junction and the resistance of the junction of a semiconductor diode
a. diode impedance b. diode ac resistance c. diode reactance d. diode ac parameter
137. The appearance of RF current oscillations in a dc-biased slab of n-type gallium arsenide in a 3.3kV electric field
a. Gunn effect b. Hall effect c. Zener effect d. Avalanche
138. Quiescent or Q-point is dependent on a. the supply voltage
b. the load resistance c. the type of diode d. All of the above
139. A germanium diode is connected to a load resistance of 1.5 kilo ohms and is supplied with 12 V such that the diode will be forward biased. What is the voltage across the diode?
a. approximately 12 v b. approximately 0.7 v c. approximately 0.3 v
d. lack of data and can’t be solved]
140. What is the drop across the diode when it is connected in series to a resistor of 1.8 kilo ohms and a supply voltage of 50 V. the supply voltage causes the diode to be reverse biased
a. 50 V b. 0.7 V c. 0.3 V
d. can’t be solved, lack of data
141. Two germanium diodes are connected in series and have a load resistance of 10 kilo ohms and a forward supply voltage of 5 V. Calculate the voltage across the load resistor.
a. 4.7 V b. 4.4 V c. 0.6 V d. 0.3 V
142. A silicon diode is in parallel with a germanium diode and is connected to a load resistor having a value of 20 kilo ohms and a forward supply voltage of 10 V. What is the approximate voltage across the silicon diode?
a. 10 V b. 1.0 V c. 0.7 V d. 0.3 V
143. What is the output voltage across a load resistor if it is paralleled with a forward biased silicon diode? The resistor network is supplied with 10 V.
a. 0.7 V b. 9.3 V c. 10 V
144. A network with a diode and a capacitor that is used to shift the dc-level of the input signal
a. clipper b. clamper c. shifter d. level inverter
145. A chopper, employing an alternately biased diode as the switching element
a. diode chopper b. active chopper c. junction chopper d. All are correct
146. A light emitting diode (LED) is to be used in a circuit with a supply voltage of 5 V. What should be the value of the resistor needed by the LED to operate normally?
a. 25 ohms b. 250 ohms c. 25 kilo ohms d. 250 kilo ohms
147. The flow of electron in a NPN transistor when used in electronic circuit is from
a. collector to base b. base to collector c. emitter to collector d. base to emitter
148. A three terminal, three layer semiconductor device that has the ability to multiply charge carriers. This device was first introduced at Bell Laboratories, by Brattain and Bardeen in 1947 and which opens a completely new direction of interest and development in the field of electronic.
a. triode b. triac c. SCR d. transistor
149. In a semiconductor device, a p-n junction formed by alloying a suitable material such as indium with the semiconductor
a. alloy junction b. diffused junction c. depletion junction d. storage junction
150. At forward-biased junction of PNP transistor, majority carriers flow heavily
a. from p- to the n-type material b. from n- to p-type material c. from p- to p-type material d. A and B above
151. Phrases “not pointing in” and “pointing in” simply means a. npn and pnp
b. pnp and npn c. npn only d. pnp only
152. The formal name of βəc
a. Common-collector reverse-current amplification factor b. Common-collector forward-current amplification factor c. Common-emitter forward-current amplification factor d. Common-emitter reverse-current amplification factor
153. At base-emitter junction, using an ohmmeter, if the positive (+) lead is connected to the base and the negative (-) lead to the emitter, a low resistance reading would indicate
a. npn transistor b. pnp transistor
c. germanium transistor d. silicon transistor
154. For an “on” transistor, the voltage VBE should be in the neighborhood of
a. 0.3 V b. 0.55 V c. 0.7 V d. 1.7 V
155. Among the three characteristics of a transistor amplifier, which region is normally employed for linear (undistorted) amplifiers?
a. active region b. cutoff region c. saturation region d. capital region
156. If the base-emitter junction is reversed biased and the base-collector junction is forward biased, the transistor will be at what region of operation?
a. active region b. cutoff region c. saturation region d. breakdown region
157. What region the transistor should be operating to have minimum distortion at the output signal?
a. active region b. cutoff region c. saturation region d. None of the above
158. Solve for the base current if the collector current is 600 mA and the current gain is 20.
a. 30 mA b. 3 mA c. 12 mA d. 1.2 mA
159. A transistor with β=100 is connected as common base; was found to have a leakage current ICBQ=1 µA. if the transistor is configured as common emitter,
what is the approximate value of its ICEO?
a. 0.01 µA b. 1.0 µA c. 100 µA d. 10 mA
160. The current gain of a transistor decreases as the operating frequency increases. As the operating frequency is increased continuously, a point occurs where the current gain becomes unity. This point, is best described by what transistor parameter?
a. unity gain frequency b. 0 dB frequency c. cutoff frequency
d. unity gain bandwidth product or unity current gain bandwidth product
161. When the base is common to both the input and output sides of the configuration and is usually the terminal closest to, or at ground potential, it is called what?
a. common-emitter terminology b. common-collector terminology c. common-base terminology d. All of these
162. Which of the transistor configuration has the highest input resistance? a. common base
b. common emitter c. common collector d. common transistor
163. One of the following amplifier characteristic refers to that of a common-base (C-B) as compared to common-emitter (C-E) and common-collector (C-C) amplifiers
a. has larger current gain b. has lower input resistance c. has higher input resistance d. has larger voltage gain
164. Most frequently used transistor configuration for pnp and npn a. common-base
b. common-collector c. common-emitter d. A and C above
165. Common-collector has the lowest power gain and a voltage gain of approximately one. In contrast to this, what configuration has the highest power gain?
a. common-base b. common-collector c. common-emitter d. emitter-follower
166. Considered as the basic FET or the simplest form of FET a. JFET
b. MOS-FET c. IGFET d. VMOS-FET
167. Junction field effect transistor or JFET has three terminals which corresponds to the E-B-C of the BJT
a. D-S-G b. D-G-S c. S-G-D d. S-D-G
168. A BJT is a current-controlled current-source device while JFET is a _______ device
a. current-controlled voltage-source b. voltage-controlled voltage-source c. voltage-controlled current-source
169. For a normal operation of an n-channel JFET, d\how do you bias the gate-source junction?
a. positive-negative respectively b. negative-positive respectively c. forward-biased
d. Any of the above
170. The current that flows into channel of a JFET when the gate-source voltage is zero
a. drain-source saturation current b. drain-source cutoff current c. drain-source leakage current d. drain-source pinch-off current
171. In FET, the conduction path of the output is controlled by the electric field as its name implies. How does an electric field in FET established?
a. By the charges present at the gate due to the reverse-biased junction b. By the application of reverse-biased between the gate and drain
c. By the charges produced due to the applied potential between drain and source VDS
d. By the charges present at each terminal due to the applied potential
172. An n-channel JFET has a drain-source saturation current IDSS=10 mA and
a gate-source pinch-off voltage Vp=-4 V. if the applied reverse gate-source voltage VGS=2 V, calculate the drain current ID.
a. 2.5 mA b. 5.0 mA c. 10.0 mA d. 22.5 mA
173. Base from Shockley’s equation of a JFET, what is the drain current when the applied voltage VGS is exactly equal to the pinch-off voltage Vp?
a. IDSS
b. maximum c. minimum d. zero
174. In MOSFET, it is the foundation upon which the device will be constructed and is formed from a silicon base
a. substrate b. slab c. source d. base
175. What type of MOSFET whose channel is originally thick but narrows as the proper gate bias is applied?
a. enhancement b. depletion c. transverse d. All of the above
176. To switch off the depletion type MOSFET, the channel should be depleted. Depletion of the channel is done by applying enough voltage across the gate-source terminal. What do you call this voltage?
a. pinch-off voltage b. trigger voltage c. holding voltage d. threshold voltage
177. The substrate used in a p-channel IGFET enhancement type a. n-type material
b. n+-type material c. p-type material d. p+-type material
178. The base material of a MOSFET which extends as an additional terminal a. source (S)
b. channel (C) c. drain (D) d. substrate (SS)
179. 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
180. Which FET operates as close as BJT in terms of switching? a. JFET
b. MOSFET depletion type c. MOSFET enhancement type d. IGFET
181. A monolithic semiconductor-amplifying device in which a high-impedance GATE electrode controls the flow of current carriers through a thin bar of semiconductor called the CHANNEL Ohmic connections made to the ends of the channel constitute SOURCE and DRAIN electrodes
a. BJT b. UJT c. FET d. UPT
182. A junction field effect transistor has a drain saturation current of 10 mA and a pinch-off voltage of -4 V. calculate the maximum transconductance
a. 2.5 mS b. 5.0 mS c. 25.0 mS d. 50.0 mS
183. What do you call an amplifier which has an output current flowing during the whole input current cycle?
a. Class AB amplifier b. Class B amplifier c. Class A amplifier d. Class C amplifier
184. If a transistor amplifier provides a 360º output signal, it is classified as a. Class A
b. Class B c. Class C d. Class D
185. An amplifier that delivers an output signal of 180º only a. Class A
b. Class B c. Class AB d. Class D
186. A full 360º sine-wave signal is applied as an input to an unknown class of amplifier, if the output delivers only a pulse of less than 180º, of what class does this amplifier belongs?
a. Class AB b. Class B c. Class C d. Class D
187. A class A amplifier has an efficiency of only 25%, but this can be increased if the output is coupled with a transformer. Up to how much is its efficiency will reach due to coupling?
a. 36.5% b. 50% c. 68.5% d. 78.5%
188. Transistorized class C power amplifiers will usually have an efficiency of a. 25%
b. 33% c. 50% d. 78.5%
189. For pulse-amplification, class D amplifier is mostly used. How efficient is a class D amplifier?
a. About 25% efficient b. Less efficient than class B
c. More efficient than class A but less efficient than class B d. Its efficiency reaches over 90%
190. An amplifier of class AB means its output signal is between the output of class B and A, such that it varies from 180º (class B) to 360º (class A). How about its efficiency?
a. Efficiency of class AB is in between the efficiency of class A and B, that is from 25%-78.5%
b. It is always as efficient as class A (25%) c. It is always as efficient as class B (78.5%)
d. The efficiency of class AB is the average of the efficiencies of both class A and class B (25%+78.5%)/2=51.75%
191. Where does the Q-point of a class C amplifier positioned? a. at saturation region
b. at active region c. at cutoff region d. below cutoff region
192. Which amplifiers can be used for linear amplification? a. Class A
b. Class B c. Class C d. Class A or B
193. What do you call an amplifier that is biased to class C but modulates over the same portion of the curve as if it were biased to class B?
a. Class S b. Class D c. Class AB d. Class BC
194. Two class B amplifiers connected such that one amplifies the positive cycle and the other amplifies the remaining negative cycle. Both output signals are then coupled by a transformer to the load.
a. transformer-coupled push-pull amplifier b. complementary-symmetry amplifier
c. quasi-complementary push-pull amplifier d. transformer-coupled class a amplifier
195. A push-pull amplifier that uses either npn or pnp as its final stage. The circuit configuration looks like the complementary-symmetry
a. transformer-coupled push-pull amplifier b. complementary-symmetry amplifier
c. quasi-complementary push-pull amplifier d. feed-back pair amplifier
196. A nonlinear distortion in which the output consists of undesired harmonic frequencies of the input signal
a. amplitude distortion b. frequency distortion c. cross-over distortion d. harmonic distortion
197. The overall gain of an amplifier in cascade is a. the sum
b. the average of each c. the product d. 100% the sum
198. A direct-coupled two-stage transistor configuration wherein the outputn of the first transistor is directly coupled and amplified by the second transistor. This configuration gives a very high current gain
a. cascade configuration b. cascode configuration c. darlington configuration d. feed-back pair
199. Famous transistor amplifier configuration designed to eliminate the so called Miller effect
a. cascode amplifier b. darlington amplifier c. differential amplifier d. complementary-symmetry
200. An amplifier basically constructed from two transistors and whose output is proportional to the difference between the voltages applied to its two inputs
a. differential amplifier b. cascode amplifier
c. complementary amplifier d. quasi-complementary amplifier
201. An amplifier having high-direct current stability and high immunity to oscillation, this is actually used to perform analog-computer functions such as summing and integrating
a. operational amplifier (op-amp) b. parametric amplifier (par-amp) c. instrumentation amplifier d. DC-amplifier
202. One of the most versatile and widely used electronic device in linear applications
a. SCR b. FET c. UJT d. Op-amp
203. It is very high-gain differential amplifier with very high input impedance and very low output impedance
a. par-amp b. op-amp
c. differential amplifier d. complementary amplifier
204. What are the possible applications of operational amplifiers (op-amps)? a. ac and dc-amplifiers
b. oscillators and signal conditioning c. voltage-level detectors and comparators d. all of the above
205. An operational amplifier must have at least how many usable terminals? a. 3 terminals
b. 5 terminals c. 8 terminals d. 14 terminals
206. The circuit at the input stage of operational amplifiers a. differential amplifier
b. cascaded amplifier c. current mirror
d. complementary amplifier
207. An amplifier whose output is proportional to the difference between the voltages applied to its two inputs
a. differential amplifier b. differencing
c. delta amplifier d. cascode-amp
208. A good op-amp has a a. very high input resistance b. very low input resistance c. very high output resistance d. very low CMRR
209. How does the input of an op-amp make high?
a. By using super beta transistor at the input differential stage b. By using FETs at the input differential stage
c. By connecting a very high resistance in series with the input differential stage
d. A and B above
210. What type of amplifier commonly used at the output stage of op-amps? a. Differential amplifier
b. Cascade amplifier
c. Complementary amplifier d. Darlington stage amplifier
211. Why do most op-amps use a common-collector at the output stage? a. To have a higher output power
b. To have a better frequency response c. To have a low harmonic distortion d. To have a very low output resistance
212. Primarily, op-amps are operated with bipolar power supply, however, we can also use single polarity supply by
a. generating a reference voltage above ground
b. “floating” the negative supply terminal (v-) of the op-amp
c. simply connecting the negative supply terminal (v-) of the op-amp to ground
d. isolating the negative supply terminal (v-) by a capacitor
213. Op-amps have two input terminals namely, the inverting (-) and non-inverting (+) inputs. What is the significance of its name?
a. If a sine-wave is applied to the inverting (-) input, the output will be inverted or shifted by 180º, while if applied to the non-inverting (+) there will be no phase shift at the output
b. If pulses are applied to the inverting (-) input, the positive pulse becomes negative at the output and vice versa, while if applied to the non-inverting (+) there will be no reversal of the pulse at the output
c. In dc-amplifier applications, increasing input at the inverting (-) terminal causes the output to decrease and vice versa, while at the non-inverting (+) input, the output magnitude goes with the input.
d. All of these are correct
214. What do you call of the gain of an op-amp if operated in common mode input?
a. differential gain b. common gain c. double-ended gain d. rejection gain
215. When one input of the op-amp is connected to ground and the other is to the signal source, its operation is called
a. single-ended output b. double-ended output c. single-ended input d. double-ended input
216. The ratio of the differential gain and common gain of an op-amp a. Differential-common mode ratio
b. Common-mode ratio
c. Differential-mode rejection ratio d. Common-mode rejection ratio
217. Calculate the CMRR of an op-amp having a common-mode gain of 10 and a differential-mode gain of 100,000 a. 1000 dB b. 100 dB c. 80 dB d. 40 dB
218. The non-inverting and inverting inputs of an op-amp have an input voltage of 1.5 mV and 1.0 mV respectively. If the op-amp has a common-mode voltage gain of 10 and a differential-mode gain of 10,000, what is its output voltage?
a. 5.0 V b. 5.0125 mV c. 5.0125 V d. 25.0125 V
219. The µA741 op-amp has a CMRR of 90 dB and a differential-mode voltage amplification of 200,000. What is the op-amp’s common-mode voltage gain?
a. 31,622.778 b. 632.40 c. 6.324 d. 0.158
220. The current needed at the input of an op-amp to operate it normally a. input bias current
b. input offset current c. input threshold current d. input holding current
221. Ideal op-amp requires no input current, but real op-amp needs a very small input current called input bias current. At both inputs, the bias currents have a slight difference. What do you call this difference?
a. Differential input current b. Differential bias
c. Input offset difference d. Input offset current
222. The reason why a slight difference between the input bias current occurs in op-amps is due to the unsymmetrical circuit component parameters. This unsymmetrical condition also produces a difference in input voltage called what?
a. Drift voltage b. Differential voltage c. Input offset voltage d. Input threshold voltage
223. Ideally, the output voltage of an op-amp is zero when there is no input signal, however, in practical circuits, a small output voltage appears, this voltage is known as
a. Minimum output voltage b. Pinch-off voltage
c. Output offset voltage d. Saturation voltage
224. Calculate the output offset voltage of an inverting amplifier using op-amp with an input offset current of 10 nA. The circuit is having an input resistance of 10 kilo ohms and a feedback resistance of 100 kilo ohms
a. 0.1 mV b. 1.0 mV c. 10.0 mV d. 100.0 mV
225. An op-amp inverting amplifier uses a feedback resistor of 100 kilo ohms and input resistor of 10 kilo ohms. If the op=amps input offset voltage is 2.0 mV, approximate the amplifier output offset voltage due to this input offset voltage
a. 10 mV b. 11 mV c. 20 mV d. 22 mV
226. The output offset voltage of an op-amp is due to the input offset current and voltage. If 1 mV is due to the input offset current and 22 mV due to the input offset voltage, what is the total output offset voltage of the op-amp?
a. 11.5 mV b. 22 mV c. 23 mV d. 45 mV
227. What is the bias-current compensating resistor in op-amp circuits?
a. A resistor used to reduce the undesired output offset voltage due to the input offset current
b. A resistor connected between the non-inverting terminal and ground c. A resistor used to balance both input bias currents and therefore eliminates
the input offset current d. All of these
228. What is the effect of the input offset voltage to the output voltage if the op-amp has no feedback element?
a. Causes the output to be always at cutoff b. Causes the output to saturate towards positive c. Causes the output to saturate towards negative
229. What is the most effective way of minimizing the output offset voltage of an op-amp?
a. By reducing the value of the feedback resistor b. By increasing the value of the input resistor c. By a capacitor-compensation technique
d. By properly using and adjusting the offset-null terminals
230. The frequency at which the open-loop gain of an op-amp is 0.707 times its value at very low frequency
a. Threshold frequency b. Break frequency c. Minimum frequency d. Operating frequency
231. The reduction of op-amps gain due to increasing operating frequency a. Cutoff
b. Roll-off
c. Diminishing factor d. Reduction step
232. A reduction of op-amp’s voltage gain by a factor of two each time the frequency doubles
a. 2 dB/octave b. 2 dB/decade c. 6 dB/octave d. 6 dB/decade
233. The low and high cutoff frequencies of an amplifier is also called a. Corner frequencies
b. 0.707 frequencies c. 3-dB frequencies
d. All of these are correct
234. An op-amp has a specified transient response rise time of 0.3 µs, calculate its unity-gain bandwidth
a. 0.857 MHz b. 1.0 MHz c. 1.167 MHz d. 2.334 MHz
235. Rise time is defined as the time required for the output voltage to rise from ____ to _____ of its final value
a. 0% - 100% b. 1% - 99% c. 5% - 95% d. 10% - 90%
236. What is the maximum signal frequency that can be used in an op-amp having a specified slew rate of 0.5 V/µsec? The maximum output voltage desired is 5 V
a. 16 kHz b. 32 kHz c. 100 kHz d. 1 MHz
237. When an op-amp is used as a comparator, the output voltage would be +VSAT if
a. V+ > V- b. V- > V+ c. V- = V+
d. V- and V+ are both zero
238. The feedback element of a differentiator constructed from op-amp is a. a resistor
b. an inductor c. a capacitor d. an RC network
239. The voltage gain of an op-amp voltage follower a. Unity
b. Rf/Ri c. 1 + Rf/Ri
d. Depends on the type of an op-amp
240. A unity-gain summing amplifier has three input, V1=1.0 mV, V2=1.5 mV and V3=2.5 mV, calculate the total output voltage
a. 2.5 mV b. 3.5 mV c. 4.0 mV d. 5.0 mV
241. In most ac-amplifiers using op-amps, the feedback resistor is shunted with a very small capacitance, what is its purpose?
a. To prevent oscillation b. To improve stability
c. To minimize high frequency noise d. To compensate for high frequency loss
242. Approximate the noise-gain of an inverting adder using op-amps if its has five inputs a. Unity (1) b. Two (2) c. Four (4) d. Six(6)
243. What is true about the external frequency-compensation capacitor? a. The higher its value, the wider is its bandwidth
b. The lower its value, the wider is its bandwidth c. The higher its value, the faster its slew rate d. A and C above
244. Typical value of the external frequency-compensating capacitor of op-amps
a. 3 – 30 nF b. 30 – 300 nF c. 0.3 – 3.0 µF d. 3.0 – 30 µF
245. Op-amps designed to operate at high slew rate, about 2000 V/µsec and at high frequencies, more than 50 MHz
a. General purpose op-amps b. High power op-amps c. High-stability op-amps
d. High-frequency, high-slew rate op-amps
246. The magnitude of the op-amps input offset voltage before it can be classified as a low-input offset voltage op-amp
a. 0.2 mV b. 2.0 mV c. 2.5 mV d. 5.0 mV
247. The most popular op-amp packages are the metal can, 8-pin DIP and the SMT. Which of these corresponds to TO-99?
a. Metal can b. 8-pin DIP c. SMT
d. All of the above
248. Dual-in-line or DIL package is designated as a. TO-99
b. TO-91 c. TO-116 d. TO-220
249. For high density ICs involving many op-amps, what packaging is suitable? a. Metal can
b. 14-pin DIL c. SMT d. Flat-pack
250. Example(s) of surface-mounted technology (SMT) devices a. PLCCs
b. SOICs c. LCCCs
d. All of the above
251. Circuits that produces alternating or pulsating current or voltage a. Damper
b. Generator c. Oscillator d. Mixer
252. What do you call the oscillator circuit that uses a tapped coil in the tuned circuit?
a. Pierce b. Colpitts c. Hartley d. Ultraudion
253. Type of oscillator whose frequency is dependent on the charge and discharge of the RC networks
a. Hartley oscillator b. Colpitts oscillator c. Relaxation oscillator d. Klystron oscillator 254. A microwave oscillator a. Hartley oscillator b. Colpitts oscillator c. Relaxation oscillator d. Klystron oscillator
255. A self-excited oscillator in which the tank is divided into input and feedback potions by a capacitive voltage divider
a. Hartley oscillator b. Colpitts oscillator c. Relaxation oscillator d. Klystron oscillator
256. A circuit usually containing two transistors or tubes in an RC-coupled amplifier, the two active devices switch each other alternately on and off
a. Multivibrator b. Signal generator c. Oscillator d. Thyristor
257. A multivibrator that generates one output pulse for each input trigger pulse a. monostable
b. astable c. bistable d. tristable
258. Monostable multivibrator is also known as a. one shot
b. single shot c. direct shot
d. one shot or single shot
259. A multivibrator having two stable states a. monostable
b. bistable c. astable d. unstable
260. It is also known as Eccles/Jordan circuit a. monostable multivibrator
b. bistable multivibrator c. astable multivibrator d. unstable multivibrator
261. Flip-flop is actually a _______ multivibrator a. monostable
b. bistable c. astable d. unstable
262. Considered as a free-running multivibrator a. monostable
b. bistable c. astable d. unstable
263. A secondary cell whose active positive plate consists of nickel hydroxide and active negative plate material is powdered iron oxide mixed with cadmium. Its typical output when fully charged is Vo=1.2 V
a. Leclanche cell b. Dry cell c. Edison cell d. Lead-acid cell
264. If a cell can be charged after it is depleted, it is considered as a. A secondary cell
b. A storage cell c. An accumulator d. All of the above
265. The maximum current a cell can deliver through a 0.01 ohm load during testing
a. Flash current b. Surge current c. Ideal current d. Full-load current
266. How long will a battery need to operate a 240 Watts equipment, whose capacity is 100 Ah and 24 volts rating?
a. 5 hrs b. 10 hrs c. 1 hr d. 0.10 hr
267. Find the output of a four (4) lead acid cells a. 3.2 V
b. 8.4 V c. 5.8 V d. 12 V
268. Silver –cadmium cell has a nominal open-circuit voltage of a. 1.05 V
b. 1.5 V c. 2.1 V d. 2.2 V
269. The flat 9-V battery has how many cells in series? a. 3
b. 4 c. 6 d. 9
270. A junction between two conductors that exhibits electrical characteristics under condition of changing temperature
a. Pn junction b. Photojunction
c. Thermoelectric junction d. Hydroelectric junction
271. Electricity that is generated due to heat, as in thermocouple a. Thermodynamics
b. Thermojunction c. Electric heater d. Thermoelectricity
272. Electrical machines refer to machines that convert a. mechanical to electrical energy
b. electrical to mechanical energy
c. electrical energy to one form of electrical energy of another form d. all of the above
273. Electrical machine that converts ac voltage to dc voltage or vice versa a. generator
b. motor
c. rotary converter d. frequency converter
274. In electrical machines, what do you call the set of conductors wound on laminated cores of good magnetic permeability?
a. Armature core b. Armature winding c. Rotary winding d. Rotary core
275. Generally, in dc generators
a. The armature winding is rotated with respect to a stationary magnetic field produced by electromagnets or permanent magnets
b. The electromagnets or permanent magnets (magnetic fields) are rotated with respect to the stationary armature winding
c. Current is sent into the armature winding; or the armature winding is usually placed in a stationary laminated iron core and the rotating element may or may not be a set of magnet poles, it depends on the type of motor d. The armature winding is supplied with current; or the armature is placed
276. Generally, in ac generators
a. The armature winding is rotated by a stationary magnetic field produced by electromagnets or permanent magnets
b. Current is sent into the armature winding; or the armature winding is usually placed in a stationary laminated iron core and the rotating element may or may not be a set of magnet poles, it depends on the type of motor c. The electromagnets or permanent magnets (magnetic fields) are
rotated with respect to the stationary armature winding
d. The armature winding is supplied with current; or the armature is placed inside a set of radially supported magnetic poles
277. In a compound generator, which field winding usually, has a lower resistance?
a. Series field winding b. Shunt field winding c. Armature winding d. Excitation winding
278. Find the frequency in kilocycles per second in the armature of a 10 pole, 1,200 rpm generator
a. 100 b. 1000 c. 10 d. 0.1
279. What should be the speed of a 6-pole ac generator in order to have a frequency of 50 Hz?
a. 100 rpm b. 500 rpm c. 1000 rpm d. 1500 rpm
280. Synchronous type of ac-motor
a. Uses a dc-generator to supply dc-excitation to the rotating field b. Uses pulsating dc
c. Uses alternator
d. Has an ac or dc depending on the type of machine 281. In dc motors, when does severe arcing happen?
a. During starting b. During rated speed c. During speed fluctuation d. During shutdown
282. In dc motors, the emf developed which opposes to the supplied voltage a. Residual emf
b. Induced emf c. Coercive emf
d. Counter emf or back emf
283. Which dc motors whose speed is greatly affected by a change in load? It will even run-away if the load is removed
a. Series b. Shunt
c. Cumulatively compounded d. Differentially compounded 284. The torque of a dc motor is
a. Directly proportional to the field strength b. Inversely proportional to the field strength c. Directly proportional to the armature current d. A and C are correct
285. One advantage of a cumulatively compounded motor is that it does not run widely at light loads, this feature is due to
a. Shunt winding b. Brake winding c. Series winding d. Clutch winding
286. Which thyristor is commonly used as motor speed control? a. Triac
b. Diac c. SCR d. SUS
287. For transformers, zero efficiency happens when it has a. No load
b. 1/2 of full load c. 2/3 of full load d. Full load
288. What are the two parameters in transformers that are the same in both primary and secondary?
a. Power and voltage b. Power and current c. Power and impedance
289. In transformers, the amount of copper used in the primary is a. Less than that of the secondary
b. Greater than that of secondary c. Exactly twice that of secondary d. Almost equal as that of secondary
290. Generally, in what application you consider the use of one-type transformers?
a. Low voltage and low current b. Low voltage and high current c. High voltage and low current d. High voltage and high current
291. _________ currents are wasteful currents which flows in cores of transformers and produces heat
a. Residual b. Eddy c. Sneak d. Magnetizing
292. In transformers, the voltage per turn at the primary is ______ the secondary
a. less than that of b. greater than that of c. a factor of
d. the same as
293. The ratio of the amount of the magnetic flux linking a secondary coil compared to the flux generated by the primary coil
a. Coupling factor b. Mutual coupling
c. Coefficient of coupling d. Hysteresis factor
294. Most electronic devices/circuits require dc-voltage to operate. A battery is a good power source, however, its operating time is limited. The use of the battery also proves to be expensive. A more practical alternative is to use the household main supply and since this is an ac-voltage, it must be converted to a dc-voltage. The circuit that converts this ac-voltage to a dc-voltage is called
a. Rectifier b. Clamper c. Filter d. Regulator
295. Find direct current voltage from a full-wave rectifier with 120 V peak rectified voltage a. 60 V b. 7.639 V c. 76.39 V d. 6.0 V
296. The dc-voltage of a full wav bridge rectifier a. 0.318 Vmax
b. 0.45 Vmax c. 0.636 Vmax d. 0.90 Vmax
297. For a power supply with a peak-=to-peak ripple voltage of 5 Vpp, determine its rms ripple
a. 1.44 Vrms b. 1.77 Vrms c. 2.88 Vrms d. 3.54 Vrms
298. Which power supply filter gives the smallest ripple voltage? a. Capacitor filter
b. RC-filter c. LC-filter
d. Multi-section LC-filter
299. A voltage regulator connected in parallel with the load a. Series regulator
b. Parallel regulator c. Shunt regulator d. Switching regulator
300. A load draws 1 A current from a 10-V regulated power supply. Calculate the power dissipated by the regulator if it has an input voltage of 16 V.
a. 6 Watts b. 10 Watts c. 12 Watts d. 16 Watts
301. Three-terminal fixed positive voltage regulators commonly used in industry
a. 78XX series b. 79XX series c. 723 IC regulator d. 317 regulator
302. The three-terminal voltage regulator such as the 78XX series has a typical current rating of 1.5 amperes. If a high current is required, say 30 amperes, how will you make modifications from this regulator in order to provide the required current?
a. By cascading them
b. By the use of a crowbar circuit c. By connecting them in parallel
d. By the use of external pass transistor 303. A crowbar circuit is used
a. To monitor the output current of a power supply and automatically shuts down the system when an overload occur
b. To monitor the temperature of a power supply and switches the cooling fan when a threshold temperature is reached
c. As voltage reference in regulated power supplies d. As an over-voltage protection in power supplies
304. In switching regulators, what are the semiconductor devices that can be used as controllable power switches?
a. BJTs and MDs b. MOSFETs and IGBT c. GTOs and thyristors d. All of the above
305. Active devices used in switching regulators may experience large over-currents during conduction (turn-on-state) and large over-voltages during turn-off. These excessive currents and voltages may cause distraction or damage of the active devices. How do we protect them?
a. By the use of a crowbar circuit b. By providing a buck-boost circuit c. by shunting a thyrector
d. by installing a snubber circuit
306. One of the major concerns in power electronics is to clean-up or shape-up the utility-voltage (the wall-outlet 220 V/60 Hz) from disturbances such as overvolt, undervolt, voltage spikes and harmonic distortions. What circuit is used for this?
a. Power conditioners b. UPS
c. Power inverters d. Line scanning
307. A power supply that continuously provides protection against undervoltage, overvoltage and even power outages
a. Standby power supply
b. Uninterruptible power supply c. Power conditioners
d. Regulated power supply
308. The art or process of determining the existence or knowing the magnitude of something, directly or indirectly in terms of a recognized standard
a. Measurement b. Testing
c. Recording d. Evaluating
309. Precision is also known as a. Correctness
b. Accuracy c. Sharpness d. Reproducibility
310. Errors due frictions of the meter movement, incorrect spring tension, improper calibration or faulty instruments
a. Observational errors b. Environmental errors c. Instrument errors d. Gross errors
311. Errors in analog meter reading due to your physical position with respect to the meter scale
a. Parallax error b. Angular error c. Linear error d. Deviation
312. What do you call the difference between any number within the set of numbers and the arithmetic mean of that set of numbers?
a. Parallax error b. Angular error c. Linear error d. Deviation
313. A permanent-magnet moving-coil instrument a. Induction instrument
b. D’ Arsonval meter movement c. Moving-iron instrument