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PCITI
8/7/2014
Model Question Bank for ELECTRONICS MECH. Trade
Page-01
BASIC ELECTRICAL & ELECTRONICS
Ques. No. 1- Resistivity of a wire depends on
(A) length (B) material (C) resistance (D) none of the above.
Ques. No. 2- Resistance of a wire is r ohms. The wire is stretched to double its length, then its resistance in ohms is
(A) r / 2 (B) 4 r (C) 2 r (D) r / 4.
Ques. No. 3-. Kirchhoff's second law is based on law of conservation of
(A) charge (B) energy (C) momentum (D) mass.
Ques. No. 4- The mass of proton is roughly how many times the mass of an electron?
(A) 184,000 (B) 184,00 (C) 1840 (D)184. (D) 0.625 x 1012
.
Ques. No. 5- Ampere second could be the unit of
(A) power (B) conductance (C) energy (D) charge.
Ques. No. 6- One kilowatt hour of electrical energy is the same as
(A) 36 x 105 watts (B) 36 x 10
s ergs (C) 36 x 10
5 joules (D) 36 x 10
5 B.T.U.
Ques. No. 7- A circuit contains two un-equal resistances in parallel
(A) current is same in both (B) large current flows in larger resistor
(C) potential difference across each is same (D) smaller resistance has smaller conductance.
Ques. No. 8- Conductance is expressed in terms of
(A) ohm / m (B) m / ohm (C) mho / m (D) mho.
Ques. No. 9- Which of the following could be the value of resistivity of copper?
(A) 1.7 x 10-8
ohm-cm (B). 1.7 x 10-6
ohm-cm (C). 1.6 x 10-5
ohm-cm (D). 1.7 x 10-4
ohm-cm
Ques. No. 10- We have three resistances of values 2 Ω, 3 Ω and 6 Ω. Which of the following combination will give an effective resistance of 4 Ω?
(A) All the three resistances in parallel
(B) 2 Ω resistance in series with parallel combination of 3 Ω and 6 Ω resistance
(C) 3 Ω resistance in series with parallel combination of 2 Ω and 6 Ω resistance
(D) 6 Ω resistance in series with parallel combination of 2 Ω and 3 Ω resistance.
Ques. No. 11- Current I in the figure is
(A) 6A (B) 5A (C) 3A (D) 2A
Ques. No. 12- Which of the following bulbs will have the least resistance ?
(A) 220 V, 60 W (B) 220 V, 100 W (C) 115 V, 60 W (D) 115 V, 100 W.
Ques. No. 13- Which method can be used for absolute measurement of resistances ?
(A)Ohm's law method (B)Wheatstone bridge method
(C)Releigh method (D) Lortentz method.
Ques. No. 14- Five resistances are connected as shown in figure below. The equivalent resistance between the points A and B will be
(A) 35 ohms (B) 25 ohms (C) 15 ohms (D) 5 ohms.
Ques. No. 15-A wire of 0.14 mm diameter and specific resistance 9.6 micro ohm-cm is 440 cm long. The resistance of the wire will be
(A) 9.6 ohm (B) 11.3 ohm (C) 13.7 ohm (D) 27.4 ohm.
Ques. No. 16- Ohm's law is not applicable to
(A) DC circuits (B) high currents (C) small resistors (D) semi-conductors.
Ques. No. 17-Specific resistance of a substance is measured in
(A) ohms (B) mhos (C) ohm-cm (D) cm/ohm.
Ques. No. 18-A wire of resistance R has it length and cross-section both doubled. Its resistance will become
(A) 4 R (B)2 R (C) R (D) R / 4.
Ques. No. 19-The element of electric heater is made of
(A) copper (B) steel (C) carbon (D) nichrome.
Ques. No.20- Three elements having conductance G1, G2 and G3 are connected in parallel. Their combined conductance will be
(A) 1/( 1/G1 + 1/G2 + 1/G3) (B) (G1G2 + G2G3 + G3G1)/(G1 + G2 + G3)
(C) 1/(G1 + G2+ G3) (D) G1 + G2 +G3
Ques. No. 21- Variable resistors are
(A)Wire wound resistors (B)Thin film resistors (C)Thick film resistors (D)All of the above.
Ques. No. 22- Temperature coefficient of resistance is expressed in terms of
(A) ohms / ohms oC (B) mhos / ohm
oC (C) mhos /
oC (D) ohms /
oC.
Ques. No. 23- Which material is expected to have least resistivity?
(A) Copper (B) Lead (C) Mercury (D) Zinc.
Ques. No. 24- A fuse is always installed in a circuit is
(A) Series (B) Parallel (C) series & parallel (D) none
Ques. No. 25- The rating of fuse wire is expressed in terms of
(A) Ohms (B) Mhos (C) Amperes (D) Watts.
Ques. No. 26- Which of the following material is not used as fuse material?
(A) Silver (B) Copper (C) Aluminium (D) Carbon.
Ques. No. 27. An immersion rod heats a bucket of water in 15 minutes. In order that the water should boil in 10 minutes
(A) length of heating element of the rod should be increased
(B) length of heating element of the rod should be reduced
(C) supply voltage should be reduced
(D) heating element of larger diameter should be used.
Ques. No. 28. Filaments of electric bulbs are usually made of
(A) Nichrome (B) Tungsten (C) Copper (D) Carbon.
Ques. No. 29- Which resistor will be physically larger in size ?
(A)10 ohm, 50 W (B) 100 ohm, 10 W (C) 1 kohm, 1 W (D) 10 Mohm, 1/ 2 W.
Ques. No. 30- 100 resistors of 100 ohms each arc connected in parallel. Their equivalent resistances will be
(A) 10,000 ohms (B) 100 ohms (C) 1 ohm (D) 1/ 10000 ohm.
Ques. No. 31- If the resistance of an incandescent light bulb changes as the voltage across the bulb is changed, which of the following is true ?
(A) The internal inductance of the bulb causes this change
(B) The bulb is said to have a low ionization potential
(C) The bulb has constant resistance of the current through the bulb is changed
(D) The bulb is a type of non-linear resistance.
Ques. No. 32- The resistance of 100 W, 200 V tamp is
(A) 100 ohm (B) 200 ohm (C) 400 ohm (D) 1600 ohm.
Ques. No. 33- Three resistance of 6 ohm each are connected as shown in Figure given below. The equivalent resistance between X1 and X2 is
(A) 2 ohm (B) 4 ohm (C) 8 ohm (D) 12 ohm.
Ques. No. 34- For the circuit shown in the figure given below, the meter will read
(A) 1 A (B) 5 A (C) 10 A (D) 25 A.
Ques. No. 35- In the color code for resistances black color represents the number
(A) 0 (B) 1 (C) 2 (D) 3.
Ques. No. 36- In the color code white color represents the number
(A) 9 (B) 8 (C) 6 (D) 5.
Ques. No. 37- In the color code number 3 is represented by
(A) blue (B) orange (C) grey (D) violet.
Ques. No. 38- The condition for the validity under Ohm's law is
(A) Temperature at positive end should be more than the temperature at negative end
(B) Current should be proportional to the size of resistance
(C) Resistance must be wire wound type
(D) Resistance must be uniform.
Ques. No. 39- In which figure the relationship between voltage V and current I is in accordance with Ohm's law ?
(A) Figure A (B) Figure B (C) Figure C (D) Figure D.
Ques. No. 40- Production of heat due to current is related by which law
(A) Ohm's law (B) Joule's law (C) Kelvin's law (D) Maxwell's law.
Ques. No. 41- A semi-conductor is
(A) one which conducts only half of applied voltage
(B) a material whose conductivity is same as between that of a conductor and an insulator
(C) a material made of alternate layers of conducting material and insulator
(D) a material which has conductivity a having average value of conductivity of metal and insulator.
(D) 0 kohm, 1W.
Ques. No. 42- A rheostat differs from potentiometer in the respect that
(A) rheostat has large number of turns
(B) rheostat offers larger number of tappings
(C) rheostat has lower wattage rating
(D) rheostat has higher wattage ratings.
Ques. No. 43- The equivalent resistance at the points X1 and X2 in the circuit shown below
(A) 60 ohm (B) 40ohm (C) 80 ohm (D) 20ohm.
Ques. No. 44- Which of the following has negative coefficient of resistance?
(A) Wire wound resistor (B) Metals (C) Non-metals (D) Thermistor.
Ques. No. 45- Certain substances lose their electrical resistance completely at finite low temperatures. Such substances are called
(A) dielectrics (B) super-conductors (C) semi conductors (D) perfect conductors.
Ques. No. 46- When checked with an ohm meter an open resistor reads
(A) zero (B) high but within tolerance (C) low but not zero (D) infinite.
Ques. No. 47- Which of the following carbon coded resistor has value of 10 kohm with 20% tolerance?
(A) Red, red, green and silver stripes
(B) Yellow, violet, yellow and silver stripes
(C) Orange, orange, black and gold stripes
(D) Brown, black, orange and no tolerance band.
Ques. No. 48- Which of the following is typical resistance and power dissipation value for a wire wound resistor?
(A) 1Mohm, 1 / 3 W (B) 50kohm, 1 / 2 W (C) 500 ohm, 1 W (D) 10 ohm, 50 W.
Ques. No. 49- A 100 kohm resistor with a 1 W power rating is likely to be a
(A) carbon resistor
(B) wire wound resistor
(C) either carbon or wire wound resistor
(D) neither carbon nor wire wound resistor.
Ques. No. 50- For a carbon-composition resistor color-coded with yellow, violet, orange and silver stripes from left to right, the value of resistance and tolerance are
(A) 470 ohm ± 10% (B) 47ohm ± 10%
(C) 740 ohm ± 50% (D) 74 ohm ± 5%.
Ques. No. 52- For a carbon-composition resistor color coded with green, black, gold and silver stripes from left to right, the resistance and tolerance are
(A) 50 ohm ± 10% (B) 5 ohm ± 5% (C) 5 ohm ± 10% (D) 0.5 ohm ± 5%.
Ques. No. 53- A resistor with the color coded value of 1000 ohms and ± 10% tolerance can have an actual resistance between
(A) 990 ohm and 1010 ohm (B)900 ohm and 1100 ohm
(C)1000 ohm and 1100 ohm (D)900 ohm and 1000 ohm.
Ques. No. 54- In a carbon resistor in case fourth stripe is not present, it can be concluded that
(A) the resistor is highly accurate (B) the resistor is defective
(C) the resistor does not contain carbon (D) the tolerance limit is ± 20 %.
Ques. No. 55- The four stripes of a resistor are yellow-violet-orange-gold. The value of resistor should be
(A) 470 ohms ± 5 % (B) 47 kilo ohm ± 5%*
(C) 47 mega ohms ± 5% (D) 4700 ohms ± 10%.
Ques. No. 56- Which of the following can have positive or negative charge?
(A) Electron (B) ion (C) Hole (D) Neutron.
Ques. No. 57- Which of the following parallel resistances will have the highest value of equivalent resistance?
(A) 10 kohm and 25 kohm (B) 1 kohm, 2 kohm and 3 kohm
(C) Two 500 kohm resistors
(D) Four 40 kohm and two 10 kohm resistors.
Ques. No. 58- In a nickel-cadmium-alkali cell the electrolyte is
(A) sulphur acid (B) potassium hydroxide
(C) zinc chloride (D) ammonium chloride.
Ques. No. 59- All good conductors have high
(A) resistance (B) electrical conductivity
(C) electrical and thermal conductivity
(D) conductance
Ques. No. 60- A light dependent resistor is basically a
(A) power resistor (B) non-metallic resistor
(C) carbon resistor (D) variable resistor.
Ques. No. 61- Voltage dependent resistors are usually made from
(A) graphite (B) charcoal (C) silicon carbide (D) nichrome.
Ques. No. 62- Voltage dependent resistors are used
(A) as current stabilizers (B) as heating elements
(C) for inductive circuits (D) to suppress surges
Ques. No. 63- In which of the following the resistance decreases with rise in temperature ?
(A) LDR (B) NTC thermistors (C) Nichrome conductors (D) ACSR conductors.
Ques. No. 64- The peak value of a sine wave occurs (A) Once each cycle at the positive maximum value. (B) Once each cycle at the negative maximum value. (C) Twice each cycle at the positive and negative maximum value. (D) Twice each cycle at the positive maximum value.
Ques. No. 65- Total opposition to current flow in a circuit with resistance and reactance is
a. Resistance
b. Reactance
c. Impedance
d. Inductance
Ques. No. 66- The imaginary part of an impedance is called:
a. Resistance
b. Reactance
c. Admittance
d. Conductance Ques.No.67- .
The battery symbol is:
A.
B.
C.
D.
Ques.No.68-.
What type of switch is this?
A. push button B. SPST C. DPDT D. SPDT
Ques.No.69. Primary batteries, unlike secondary batteries, may be: A. charged once B. used once C. recharged over and over D. stored indefinitely
Ques.No.70. In practical applications, battery voltage: A. is restored as soon as disconnect occurs B. is lowered as the load increases C. may be stored indefinitely D. will be reduced to zero as power is drawn
Ques.No.71. The negative and positive charge symbols are assigned (in that order) to the: A. proton and electron B. electron and proton C. atom and nucleus D. electron and element
Ques.No.72. A voltmeter is used: A. to measure current B. in series with the circuit C. in parallel with the circuit D. to measure coulombs
Ques.No.73. If the current in a circuit equals 0 A, it is likely that the A. voltage is too high B. resistance is too low C. circuit has a short D. circuit is open
Ques.No.74. Current equals:
A.
B. coulombs × time
C.
D. voltage × time
Ques.No.75. What are the unit and symbol for current? A. Ampere, A B. Coulomb, I C. Ampere, Q D. Ampere, I
Ques.No.76. Which part of an atom has no electrical charge? A. Electron B. Neutron C. Proton D. All of the above
Ques.No.77. Which voltage source converts chemical energy to electrical energy? A. Electrical generator B. Battery C. Solar cell D. Electronic power supply
Ques.No.78. An example of potential energy is: A. tea-kettle steam B. a moving vehicle C. the sun D. a battery
Ques.No.79. If 40 C of charge flow past a point in 20 s, what is the current? A. 2 A B. 0.5 A C. 20 A D. 40 A
Ques.No.80. Batteries differ from fuel cells in that A. a battery is a closed system B. a battery uses hydrogen and oxygen to create electricity C. a battery uses a polymer electrolyte membrane D. none of the above
Ques.No.81. The removal of a non-neutral subatomic particle converts the atom into a: A. charged ion B. nucleus C. heavier element D. compound
Ques.No.82. One coulomb passing a point in one second is one: A. ampere B. volt C. ohm D. charge
22. In which states may matter may be found? A. solid, liquid, or mineral B. solid, gas, or liquid C. mineral, gas, or liquid D. plastic, solid, or gas
Ques.No.83. Material that consists of a mixture of elements is considered to be: A. an element B. an ion C. a compound D. a molecule
Ques.No.84. How many valence shell electrons are there in semiconductor atoms? A. 16 B. 8 C. 4 D. 2
Ques.No.85. When considering conventional current versus electron current flow: A. electron current flow came first B. protons move in conventional current flow C. conventional current flow came first D. the direction of current is the same in both methods
Ques.No.86. Which unit of charge contains 6.25 × 1018
electrons? A. An ampere B. A coulomb C. A volt D. A joule
Ques.No.87. A switch is a device that: A. short circuits complex circuits B. holds a fuse C. has double poles D. opens or completes a current path
Ques.No.88. The term used to designate electrical pressure is: A. voltage B. current C. resistance D. conductance
Ques.No.89. Which electronics material opposes the movement of free electrons? A. Conductor B. Insulator C. Semiconductor D. Element
Ques.No.90. Current is considered as the movement of: A. electrons B. protons C. charge D. nuclei
Ques.No.91. The charge of one coulomb is equal to: A. 6.24 x 10
−18 electrons
B. one ampere C. one second D. 6.24 x 10
18 electrons
Ques.No.92. A basic electric circuit is made up of what components? A. A load, a resistor, and a conductive path for current B. A voltage source, a load, and a conductive path for current C. A voltage source, a conductive path for current, and a battery D. A conductive path for current, a battery, and a copper wire
Ques.No.93. An ammeter is used to measure A. voltage B. current C. resistance D. All of the above
Ques.No.94. What is the name of the pressure that moves electrons in a closed circuit? A. amperes B. ohms C. voltage D. coulombs
Ques.No.95. What are the basic building blocks that all matter is composed of? A. electrons, neutrons, and protons B. two protons for each neutron C. two protons for each electron D. electrons, neutrons, and charged ions
Ques.No.96. What is a characteristic of a secondary cell? A. rechargeability B. not rechargeable C. a dry cell D. non-liquid
Ques.No.97. If a fluid system is compared to an electrical system, the fluid pump will correspond to a: A. conductor B. lamp C. battery D. insulator
Ques.No.98. An element is a substance that is: A. varied throughout the entire piece B. used only in electronics C. electrically charged D. found only in its pure form
Ques.No.99. Current is: A. the presence of a positive charge B. the abundance of electrons C. the movement of electrons D. the repulsion of electrons
Ques.No.100. What do you call a diagram that shows the electrical connections of a circuit's components? A. A schematic diagram B. A pictorial diagram C. A block diagram D. An electrical diagram
Ques.No.101. A short circuit will have: A. a small current flow B. a large current flow C. no current flow D. some current flow
Ques.No.102. The basic difference between a fuse and a circuit breaker is A. a fuse is slower B. a fuse is reusable C. a circuit breaker is reusable D. a circuit breaker is more reliable
Ques.No.103. Which is the smallest? A. atom B. proton C. neutron D. electron
Ques.No.104. A secondary cell generates dc via chemical activity; a primary cell generates dc: A. electrically B. thermally C. optically D. chemically
Ques.No.105. Which of the following statements is true? A. Unlike charges repel and like charges attract. B. Like charges repel and unlike charges attract. C. Unlike charges attract and like charges attract. D. Like charges repel and unlike charges repel.
Ques.No.106. If an electrical system is compared to a fluid system, the electrical current corresponds to the: A. pressure B. pump C. water wheel D. water flow
Ques.No.107. The unit for voltage is the ___ and the symbol for voltage is ___. A. joule, V B. coulomb, J
C. volt, Q D. volt, V
Ques.No.108. A connection to the frame of a piece of electronic equipment is sometimes referred to as ___ ground. A. a chassis
B. an earth
C. a circuit
D. either chassis or circuit
Ques.No.109. Fuses and circuit breakers are designed to ___ when excessive current flows. A. buzz B. illuminate
C. close D. open
Ques.No.110. The capacity of a battery cell is measured by the amount of __________ that can be supplied over time. A. current B. voltage
C. coulombs D. joules
Ques.No.111. A rheostat is ___. A. a three-terminal device that controls current
B. a two-terminal device that controls current
C. a two-terminal device that divides voltage
D. a three-terminal device that divides voltage
Ques.No.112. If an electronic component fails by developing an open circuit, the current will __________. A. increase B. decrease
C. cease D. not change
Ques.No.113. ___ make electric current possible. A. Protons B. Neutrons
C. Shells D. Free electrons
Ques.No.114. The ___ is placed in series with the flow of current. A. voltmeter B. ammeter
C. ohmmeter D. wattmeter
Ques.No.115. The ___ represents a negative charge in an atom. A. electron B. proton
C. neutron D. None of the above
Ques.No.116. An atom of a semiconductor has _______________ electrons in the valence shell. A. 4 B. 8
C. 2 D. 0
Ques.No.117. An atom with more electrons than protons is ___. A. a positive ion
B. a balanced atom
C. a negative ion
D. not possible
Ques.No.118. All resistors can be placed into one of two main categories: ___ or ___. A. carbon film, metal film
B. fixed, variable
C. wire wound, carbon-composition
D. insulator, semiconductor
Ques.No.119. Voltage is _________. A. the opposition to the flow of current
B. the movement of free electrons
C. the force that exists between charged particles
D. the force that causes water to flow
Ques.No.120. A ___ resistor has color bands of yellow, violet, yellow, gold. A. 470 5%
B. 5.7 M 5%
C. 37 k 5%
D. 470 k 5%
Ques.No.121. The unit for resistance is the ___ and the symbol for resistance is ___. A. ampere, R B. ohm, R
C. volt, Q D. ohm, J
2- ALTERNATING CURRENT & VOLTAGE
Ques.No.122.
What type of waveform is shown in the given circuit? A. Sine wave
B. Square wave
C. Triangle wave
D. Sawtooth wave
Ques.No.122. .
What is the peak-to-peak voltage of the waveform in the given circuit? A. 2 V
B. 4 V
C. 6 V
D. 8 V
Ques.No.123. . A half-cycle average voltage of 12 V is equal to what rms voltage?
A. 13.33 V
B. 8.48 V
C. 18.84 V
D. 7.64 V
Ques.No.124. What is the instantaneous peak voltage at 250° on a 6 V peak sine wave?
A. +5.64 V
B. –5.64 V
C. +26.13 V
D. –26.13 V
Ques.No.125.
Calculate the positive-going slope of the waveform in the given circuit. A. 5 V/ms
B. 2.5 V/ms
C. 2.5 V/s
D. 5 V/s
Ques.No.126. A rectangular wave that has a duty cycle of 50% could be called a
A. "c" wave
B. sawtooth wave
C. square wave
D. triangular wave
Ques.No.127 . The effective value of a sine wave is equal to
A. 0.707 of peak voltage
B. 0.636 of peak voltage
C. sin 45° of peak voltage
D. both 0.707 of peak voltage and sin 45° of peak voltage
Ques.No.128 .
What is the dc voltage of the waveform in the given circuit? A. 2 V
B. 4 V
C. 6 V
D. 8 V
Ques.No.129 . What is the fourth harmonic of a fundamental frequency of 400 Hz?
A. 100 Hz
B. 4 kHz
C. 4 Hz
D. 1.6 kHz
Ques.No.130 . A single-phase induction motor
A. is self-starting
B. operates at a fixed speed
C. is less reliable than a three-phase synchronous motor
D. none of the above
3- RL CIRCUIT
Ques.No.131. As frequency increases A. both series and parallel RL impedance decrease
B. series RL impedance decreases and parallel RL impedance increases
C. series RL impedance increases and parallel RL impedance decreases
D. both series and parallel RL impedance increase
Ques.No.132.
Calculate the voltage dropped across R1 in the given circuit. A. 14 V
B. 26.8 V
C. 28 V
D. 0 V
Ques.No.133. What is the true power of a 24 Vac parallel RL circuit when R = 45 and XL =
1100 ?
A. 313.45 W
B. 12.8 W
C. 44.96 W
D. 22.3 W
Ques.No.134. If XL= 100 and R = 100 , then impedance will be
A. 141.4
B. 14.14
C. 100
D. 200
4-TIME RESPONSE OF REACTIVE CIRCUITS
Ques.No.136.
What voltage will the capacitor charge up to in the given circuit for the single input
pulse shown? A. 3.15 V
B. 4.3 V
C. 4.75 V
D. 4.9 V
Ques.No.137. An RL integrator and an RC differentiator can act as what types of filters,
respectively?
A. low-pass, low-pass
B. low-pass, high-pass
C. high-pass, high-pass
D. high-pass, low-pass
Ques.No.138. What is a circuit that produces short-duration spikes?
A. A trigger pulse generator
B. An RL integrator
C. A timing circuit
D. A pulse waveform-to-dc converter
Ques.No.139.
The given circuit is an A. RL integrator
B. RC differentiator
C. RL differentiator
D. RC integrator
Ques.No.140. Which of the following is true for a capacitor?
A. A capacitor acts like a short to instantaneous changes in current.
B. A capacitor's voltage cannot change instantaneously.
C. A capacitor acts like an open to dc.
D. All of the above
Ques.No.141. If the capacitor in an RC integrator shorts, the output
A. is at ground
B. would measure the same as the input
C. would measure zero volts
D. None of the above
Ques.No.142.
How long will it take the capacitor in the given circuit to discharge?
A. 16.4 s
B. 32.8 s
C. 65.6 s
D. 82 s
1. What are the two main applications for ac? A. direct, pulsating
B. electric, magnetic
C. power, information
D static, dynamic
2.The distance that a signal's energy can travel in the time it takes for one cycle to occur is
called the signal's: A. amplitude B. frequency
C. wavelength D. period
3. One oscilloscope selector knob that allows the major and minor divisions of the graticule to be
used to determine a signal amplitude value is called the: A. time/cm control
B. position control
C. intensity control
D volts/cm control
4. If current varies periodically from zero to a maximum, back to zero, and then repeats, the
signal is:
A. direct B. alternating
C. pulsating D. repetitive
5. What voltage will an ac voltmeter display? A. rms B. average
C. peak D. peak-to-peak
6. What is the peak value of a household appliance that uses a 230 V ac source? A. 163 V
B. 230 V
C. 325 V
D. 480 V
7. What is the waveform period difference between the 60 Hz electricity used in this country
and the 50 Hz used in Europe? A. 3 ms
B. 16 ms
C. 4 ms
D. 20 ms
10. A sine wave reaches maximum positive voltage at:
A. 90° B. 0°
C. –90° D. 360°
12. What is the average value of a 12 V peak wave? A. 3.82 V
B. 4.24 V
C. 7.64 V
D. 9.42 V
13. A test equipment item that has the ability to produce either square, triangular, or sawtooth
waveforms is called:
A. a function generator
B. a radio frequency generator
C. an audio frequency generator
D. a frequency meter or counter
14. The current is flowing in what direction?
A. clockwise
B. counterclockwise
C. in both directions at the same time
D. 50% of the time clockwise and 50% of the time counterclockwise
15. What does the CRT oscilloscope display?
A. voltage and period
B. current and frequency
C. rms voltage and current
D. frequency and voltage
16. Power companies supply ac, not dc, because:
A. it is easier to transmit ac
B. there is no longer a need for dc
C. dc is more dangerous
D. there are not enough batteries
17. If a waveform period is determined to be 10 microseconds in duration, what is the frequency of
the signal?
A. 100 Hz
B. 1000 Hz
C. 10 kHz
D. 100 kHz
19. If a sine wave signal is 100 mV peak-to-peak, how many volts would be measured by a voltmeter?
A. 14.14 mV
B. 35.4 mV
C. 63.7 mV
D. 70.7 mV
20. What term expresses the frequency of a rectangular wave?
A. Hz B. period
C. PRF D. PRT
21. AC effective voltage is named:
A. average
B. peak
C. peak-to-peak
D. root mean square
22. If a voltmeter measures a sine wave as 500 mV, what would be its average value?
A. 159.0 mV
B. 318.5 mV
C. 353.5 mV
D. 451.0 mV
23. One adjustable knob on the oscilloscope that allows the trace to be aligned with a reference
graticule is called the:
A. position control
B. focus control
C. intensity control
D. volts/cm control
24. Signal comparisons may be most easily seen when using which item of test equipment?
A. spectrum analyzer
B. multimeter
C. function generator
D. dual trace oscilloscope
25. The magnitude that an alternation varies from zero is called its:
A. altitude B. amplitude
C. attitude D. polarity
26. The power that is distributed from a power plant to your home is:
A. high voltage to high voltage
B. low voltage to high voltage
C. high voltage to low voltage
D. low voltage to low voltage
27. A rectangular wave that has a duty cycle of 50 percent could be called a:
A. c wave
B. sawtooth wave
C. square wave
D. triangle wave
28. A triangle wave consists of repeating:
A. positive ramps only
B. negative ramps only
C. positive and negative ramps of equal value
D. positive and negative ramps of unequal value
29. What is the name of a device used to directly measure the frequency of a periodic wave?
A. oscilloscope
B. frequency meter or counter
C. audio frequency generator
D. radio frequency generator
30. Which control should be moved to display more cycles of a signal on an oscilloscope?
A. horizontal position to left or right
B. volts/cm to a smaller number
C. vertical position to top or bottom
D. time/cm to a higher setting
31. What is the name of a device that converts sound waves to electrical waves?
A. an amplifier
B. an antenna
C. a filter
D. a microphone
32. If the frequency of a radio wave is increased, then its wavelength will:
A. increase
B. decrease
C. remain the same
D. cannot tell
34. What is the peak-to-peak current value when an ammeter measures a 20 mA value?
A. 14 mA
B. 28 mA
C. 40 mA
D. 57 mA
37. A sine wave has:
A. four quadrants
B. two alternations
C. one period
D. all of the above
39. One oscilloscope selector knob that allows the major and minor divisions of the graticule to be
used to determine a waveform period is called a:
A. focus control
B. time/cm control
C. intensity control
D. volts/cm control
40. What is the period of a 16 MHz sine wave?
A. 196 ns
B. 62.5 ns
C. 31.25 ns
D. 19.9 ns
5- DIODES AND APPLICATIONS
1. What is a varistor?
A. a voltage-dependent resistor
B. a voltage-dependent diode
C. a current-dependent resistor
D. a current-dependent diode
2. Which type of transformer is required to create a 180 degree input to a rectifier? A. center-tapped secondary
B. step-down secondary
C. stepped-up secondary
D. split winding primary
3. What circuit activity may shift a characteristic curve so that diode operating points are
different? A. higher power (heat)
B. higher resistance
C. lower voltage
D. lower current
4. What is wrong with this diode?
A. open
B. short
C. nothing
D. not enough data
5. The dc current through each diode in a bridge rectifier equals: A. the load current
B. half the dc load current
C. twice the dc load current
D. one-fourth the dc load current
6. When matching polarity connections have been made and the potential difference (PD) is
above 0.7 V, the diode is considered to be: A. not working
B. forward biased
C. reverse biased
D. an open switch
7. In a power supply diagram, which block indicates a smooth dc output? A. transformer B. filter
C. rectifier D. regulator
8. If a 169.7 V half-wave peak has an average voltage of 54 V, what is the average of two full-
wave peaks? A. 119.9 V
B. 108.0 V
C. 115.7 V
D. 339.4 V
9. What is the current through the LED?
A. 0 mA
B. 23 mA
C. 18 mA
D. 13 mA
10. The characteristic curve for the complex model of a silicon diode shows that A. the barrier potential is 0 V
B. the barrier potential stays fixed at 0.7 V
C. the barrier potential increases slightly with an increase in current
D. the barrier potential decreases slightly with an increase in current
11. Since diodes are destroyed by excessive current, circuits must have: A. higher voltage sources
B. current limiting resistors
C. more dopants
D. higher current sources
12. A diode for which you can change the reverse bias, and thus vary the capacitance is called a A. varactor diode
B. tunnel diode
C. zener diode
D.
switching diode
13. A filtered full-wave rectifier voltage has a smaller ripple than does a half-wave rectifier
voltage for the same load resistance and capacitor values because: A. there is a shorter time between peaks
B. there is a longer time between peaks
C. the larger the ripple, the better the filtering action
D. none of the above
14. Testing a good diode with an ohmmeter should indicate A. high resistance when forward or reverse biased
B. low resistance when forward or reverse biased
C. high resistance when reverse biased and low resistance when forward biased
D. high resistance when forward biased and low resistance when reverse biased
15. The peak inverse voltage (PIV) across a nonconducting diode in a bridge rectifier equals
approximately: A. half the peak secondary voltage
B. twice the peak secondary voltage
C. the peak value of the secondary voltage
D. four times the peak value of the secondary voltage
16. What is the current through the diode?
A. 1 mA
B. 0.975 mA
C. 0.942 mA
D. 0.0 mA
17. Electrons in the outermost orbit or shell of an atom are called A. free electrons
B. negative ions
C. valence electrons
D. conduction band electrons
18. Shunting the ac component away from the load is the task of a: A. transformer B. filter
C. regulator D. rectifier
19. A pn junction allows current flow when A. the p-type material is more positive than the n-type material
B. the n-type material is more positive than the p-type material
C. both the n-type and p-type materials have the same potential
D. there is no potential on the n-type or p-type materials
20. What is the current through the zener diode?
A. 0 mA
B. 7 mA
C. 8.3 mA
D. 13 mA
21. When a diode is forward biased, the voltage across it A. is directly proportional to the current
B. is inversely proportional to the current
C. is directly proportional to the source voltage
D. remains approximately the same
22. Why is heat produced in a diode? A. due to current passing through the diode
B. due to voltage across the diode
C. due to the power rating of the diode
D. due to the PN junction of the diode
23. The arrow in the schematic symbol of a diode points to A. the n-type material, which is called the anode
B. the n-type material, which is called the cathode
C. the p-type material, which is called the anode
D. the p-type material, which is called the cathode
24. The diode schematic arrow points to the: A. trivalent-doped material
B. positive axial lead
C. anode lead
D. cathode lead
25. When checking a diode, low resistance readings both ways indicate the diode is:
A. open
B. satisfactory
C. faulty
D. not the problem
26. In a diode schematic, the anode is represented by a(n): A. triangle
B. vertical line
C. zig-zag line
D. element indicator
27. An IC regulator receives an overload; it will: A. shut down
B. compensate for heat
C. provide more voltage
D. sample and adjust
28. With full-wave rectification, current through the load resistor must be: A. in opposite directions
B. to the external load
C. from the reverse biased diode
D. in the same direction
29. A characteristic curve is the result of a current versus voltage plot of diode activity, which
begins at the: A. 3rd quadrant
B. current plot
C. graph origin
D. voltage plot
30. Rectifier output polarity depends upon: A. cycles of input
B. capacitor polarity
C. half or full wave
D. diode installation
31. With a 12 V supply, a silicon diode, and a 370-ohm resistor in series, what voltage will be
dropped across the diode? A. 0.3 V
B. 0.7 V
C. 0.9 V
D. 1.4 V
32. If the frequency of the applied ac signal to a half-wave rectifier is 60 Hz, the frequency of the
pulsating dc output will be A. 30 pps
B. 60 pps
C. 90 pps
D. 120 pps
33. What is the peak output voltage for this half-wave rectifier?
A. 1 V
B. 7.8 V
C. 10.9 V
D. 15.6 V
34. Thermal shutdown occurs in an IC regulator if: A. power dissipation is too high
B. internal temperature is too high
C. current through the device is too high
D. load resistance increases
35. The conduction band is closest to the valence band in A. semiconductors
B. conductors
C. insulators
D. The distance is the same for all of the above.
36. What is the percent of regulation if Vnl = 20 V and Vfl = 19.8 V? A. 0% B. 1%
C. .1% D. 5%
37. With a half-wave rectified voltage across the load resistor, load current flows for what part of
a cycle? A. 0 degrees
B. 90 degrees
C. 180 degrees
D. 360 degrees
38. Which of the following circuits would require the least amount of filtering? A. A half-wave rectifier
B. A full-wave rectifier
C. A bridge rectifier
D. A full-wave rectifier and a bridge rectifier
39. What is wrong with this circuit?
A. The zener is open.
B. The zener is shorted.
C. nothing
D. not enough data
40. The voltage where current may start to flow in a reverse-biased pn junction is called the A. breakdown voltage
B. barrier potential
C. forward voltage
D. biasing voltage
41. Providing a constant output regardless of ac input or load resistance changes is the function of
a: A. transformer B. filter
C. regulator D. rectifier
42. When a diode is destroyed it has infinite impedance. When damaged by heat it will probably: A. short
B. conduct more
C. conduct less
D. open
43. The area at the junction of p-type and n-type materials that has lost its majority carriers is
called the A. barrier potential
B. depletion region
C. n region
D. p region
44. DC power should be connected to forward bias a diode as follows: A. – anode, + cathode
B. – cathode, – anode
C. + anode, – cathode
D. + cathode, + anode
45. At any given time in an intrinsic piece of semiconductor material at room temperature A. electrons drift randomly
B. recombination occurs
C. holes are created
D. All of the above
46. In a power supply diagram, which block indicates a pulsating dc output? A. transformer B. filter
C. rectifier D. regulator
47. List three diode packages: A. clip package, DIP, small current package
B. DIP, small current package, large current package
C. small current package, large current package, and SIP
D. small current package, large current package, clip package
1.
A ___ is created when an electron moves from the valence band to the conduction band.
A. Hole* B. gap
C. vacancy D. blank
2. The average value of the half-wave rectified output voltage is approximately __________ of
Vp. A. 31.8%* B. 63.6%
C. 70.7% D. 100%
3. Typically the forward voltage on an LED is between _______ and ________. A. 1.5 V, 3.7 V
B. 0.7 V, 1.1 V
C. 1 V, 3 V*
D. 1 V, 6 V
4. A two-diode rectifier will not operate without a _________. A. center-tapped transformer*
B. voltage regulator
C. capacitive filter
D. phase-inverting transformer
5.
The name of the circuit in the given circuit is the ___. A. half-wave rectifier
B. center-tapped full-wave rectifier
C. full-wave bridge rectifier*
D. half-wave bridge rectifier
6. The small amount of ac signal present on the output of a filtering network for a dc power
supply is known as ________. A. pulsating dc
B. trickle
C. Ripple*
D. waffle
7.
The peak output voltage from the circuit in the given circuit equals ___. A. 3 V
B. 3.7 V
C. 2.3 V*
D. 0 V
8. An electron can move to another atom's orbit only while in the _______. A. valence band
B. conduction band*
C. orbit nearest the nucleus
D. covalent band
9.
The average value of the output voltage from the circuit in the given circuit equals ___. A. 5.48 V*
B. 2.74 V
C. 0 V
D. 6.37 V
10.
Atoms in a silicon crystal are held together by ___ bonds. A. crystal B. chemical
C. electrical D. Covalent*
11. Special diodes designed to conduct in the reverse direction are called _______________
diodes. A. Zener* B. varactor
C. LED D. switching
12. ___ occurs when a pn junction is first formed. A. Recombination*
B. Covalent bonding
C. Crystallization
D. Breakdown
13.
Connecting a capacitor filter to the circuit in the given circuit will___. A. produce a nearly-constant dc voltage*
B. reduce the output voltage
C. increase the ripple voltage
D. lower the surge current
14.
The peak inverse voltage (PIV) for the diode in the give circuit equals ___. A. 3 V*
B. 2.3 V
C. 0 V
D. 6 V
15. A pure semiconductor material ___ very well. A. conducts
B. insulates
C. conducts and insulates
D. neither conducts nor insulates*
16. The small amount of ac signal present on the output of a filtering network for a dc power
supply is known as ________. A. pulsating dc
B. trickle
C. Ripple*
D. waffle
6- BIPOLAR JUNCTION TRANSISTORS (BJT)
1. When transistors are used in digital circuits they usually operate in the: A. active region
B. breakdown region
C. saturation and cutoff regions
D. linear region
2. Three different Q points are shown on a dc load line. The upper Q point represents the:
A. minimum current gain
B. intermediate current gain
C. maximum current gain
D. cutoff point
3. A transistor has a of 250 and a base current, IB, of 20 A. The collector current, IC, equals:
A. 500 A
B. 5 mA
C. 50 mA
D. 5 A
4. A current ratio of IC/IE is usually less than one and is called:
A. beta B. theta
C. alpha D. omega
5. With the positive probe on an NPN base, an ohmmeter reading between the other transistor
terminals should be:
A. open
B. infinite
C. low resistance
D. high resistance
6. In a C-E configuration, an emitter resistor is used for:
A. stabilization
B. ac signal bypass
C. collector bias
D. higher gain
7. Voltage-divider bias provides:
A. an unstable Q point
B. a stable Q point
C. a Q point that easily varies with changes in the transistor's current gain
D. a Q point that is stable and easily varies with changes in the transistor’s current gain
8. To operate properly, a transistor's base-emitter junction must be forward biased with reverse bias
applied to which junction?
A. collector-emitter B. base-collector
C. base-emitter D. collector-base
9. The ends of a load line drawn on a family of curves determine:
A. saturation and cutoff
B. the operating point
C. the power curve
D. the amplification factor
10. If VCC = +18 V, voltage-divider resistor R1 is 4.7 k , and R2 is 1500 , what is the base bias
voltage?
A. 8.70 V
B. 4.35 V
C. 2.90 V
D. 0.7 V
11. The C-B configuration is used to provide which type of gain?
A. voltage B. current
C. resistance D. power
12. The Q point on a load line may be used to determine:
A. VC B. VCC
C. VB D. IC
13. A transistor may be used as a switching device or as a:
A. fixed resistor
B. tuning device
C. rectifier
D. variable resistor
14. If an input signal ranges from 20–40 A (microamps), with an output signal ranging from .5–1.5
mA (milliamps), what is the ac beta?
A. 0.05 B. 20
C. 50 D. 500
15. Which is beta's current ratio?
A. IC/IB B. IC/IE
C. IB/IE D. IE/IB
16. A collector characteristic curve is a graph showing:
A. emitter current (IE) versus collector-emitter voltage (VCE) with (VBB) base bias voltage held constant
B.
collector current (IC) versus collector-emitter voltage (VCE) with (VBB) base bias voltage held
constant
C. collector current (IC) versus collector-emitter voltage (VC) with (VBB) base bias voltage held constant
D.
collector current (IC) versus collector-emitter voltage (VCC) with (VBB) base bias voltage held
constant
17.With low-power transistor packages, the base terminal is usually the:
A. tab end
B. middle
C. right end
D. stud mount
18. When a silicon diode is forward biased, what is VBE for a C-E configuration?
A. voltage-divider bias
B. 0.4 V
C. 0.7 V
D. emitter voltage
19. What is the current gain for a common-base configuration where IE = 4.2 mA and IC = 4.0 mA?
A. 16.80 B. 1.05
C. 0.20 D. 0.95
20. With a PNP circuit, the most positive voltage is probably:
A. ground B. VC
C. VBE D. VCC
21. If a 2 mV signal produces a 2 V output, what is the voltage gain?
A. 0.001 B. 0.004
C. 100 D. 1000
22. The symbol hfe is the same as:
A.
B.
C. hi-fi
D.
23. Most of the electrons in the base of an NPN transistor flow:
A. out of the base lead
B. into the collector
C. into the emitter
D. into the base supply
24. In a transistor, collector current is controlled by:
A. collector voltage
B. base current
C. collector resistance
D. all of the above
25. Total emitter current is:
A. IE – IC
B. IC + IE
C. IB + IC
D. IB – IC
26. Often a common-collector will be the last stage before the load; the main function(s) of this
stage is to:
A. provide voltage gain
B. provide phase inversion
C. provide a high-frequency path to improve the frequency response
D.
buffer the voltage amplifiers from the low-resistance load and provide impedance matching for
maximum power transfer
27. For a C-C configuration to operate properly, the collector-base junction should be reverse biased,
while forward bias should be applied to which junction?
A. collector-emitter B. base-emitter
C. collector-base D. cathode-anode
28. The input/output relationship of the common-collector and common-base amplifiers is:
A. 270 degrees
B. 180 degrees
C. 90 degrees
D. 0 degrees
29. If a transistor operates at the middle of the dc load line, a decrease in the current gain will move
the Q point:
A. off the load line
B. nowhere
C. up
D. down
30. Which is the higher gain provided by a C-E configuration?
A. voltage B. current
C. resistance D. power
31. What is the collector current for a C-E configuration with a beta of 100 and a base current of 30
A?
A. 30 A
B. .3 A
C. 3 mA
D. 3 MA
2. In this analog amplifier the input is in phase with the output.
A. True B. False
3. The voltage measured from the collector to the emitter is the sum of the voltage base-emitter
plus the voltage collector-base. A. True B. False
4. This is a PNP transistor.
A. True B. False
5. A transistor used in a digital circuit will have two operating states, which are cutoff and
saturation. A. True B. False
6. When a transistor is operating as a variable resistor it has transistance. A. True B. False
7. In a BJT, the collector current is approximately equal to the base current.
A. True B. False
8. The voltage gain of a transistor is inversely proportional to the change in output current. A. True B. False
9. The three bipolar transistor circuit configurations are common-base, common-emitter, and
emitter-follower. A. True B. False
10. When troubleshooting a bipolar junction transistor using an ohmmeter, if one of the junctions
reads low in both directions, the junction is shorted and the transistor is bad. If one of the
junctions reads high in both directions, the junction is shorted and the transistor is good. A. True B. False
11. BJTs are "junction" transistors because they use current-carrying P-N junctions. A. True B. False
12. The voltage measured from the collector to the emitter is the sum of the base-emitter voltage
plus the collector-base voltage. A. True B. False
13. Transistors are controlled to operate as a switch or to operate as a variable resistor. A. True B. False
14. If this circuit were used in a digital circuit, it would be a NOT gate.
A. True B. False
15. A common-emitter (C-E) is so called because the emitter is connected to both the input and
output signals. A. True B. False
16. Current gain in a transistor is inversely proportional to collector current. A. True B. False
17. In a common-base (C-B) amplifier, the output is 180 degrees out of phase with the input. A. True B. False
18. A bipolar transistor has three leads: the base, collector, and emitter. A. True B. False
19. The polarity of VBE is such that it reverse biases the base-emitter junction. A. True B. False
20. With a common-collector (C-C) amplifier the input is applied to the base and the output is
taken from the emitter. A. True B. False
21. In a BJT, the collector current is approximately equal to the base current. A. True B. False
1. The input resistance of the base of an emitter-follower is usually _________.
A. very low
B. very high
C. shorted to ground
D. open
2. The phase difference between the input and output ac voltage signals of a common-emitter
amplifier is __________. A. 0º B. 90º
C. 180º D. 360º
3. Base bias provides _________. A. a very stable Q point
B. a very unstable Q point
C. no current gain
D. zero current in the base and collector circuits
4. VCE approximately equals ________ when a transistor switch is cut off. A. VCC
B. VB
C. 0.2 V
D. 0.7 V
5. The input resistance, Rin of a common-collector amplifier, consists of ____________. A. Rin = RE × AC Current Gain
B.
C. Rin = RE ×
D. none of the above
6. The signal voltage gain of an amplifier, AV, is defined as __________.
A.
B. AV = IC x RC
C.
D.
7. VCE approximately equals ________ when a transistor switch is in saturation. A. VC
B. VB
C. 0.3 V
D. 0.7 V
8. An emitter-follower has a voltage gain that is __________. A. much less than one
B. approximately equal to one
C. greater than one
D. zero
7- OPERATIONAL AMPLIFIERS
Ques.No.143. An ideal operational amplifier has
A. infinite output impedance
B. zero input impedance
C. infinite bandwidth
D. All of the above
Ques.No.144. Another name for a unity gain amplifier is:
A. difference amplifier
B. comparator
C. single ended
D. voltage follower
Ques.No.145. The open-loop voltage gain (Aol) of an op-amp is the
A. external voltage gain the device is capable of
B. internal voltage gain the device is capable of
C. most controlled parameter
D. same as Acl
Ques.No.146. What is the output waveform?
A.
sine wave
B. square wave
C. sawtooth wave
D. triangle wave
Ques.No.147. What is this circuit?
A. a low-pass filter
B. a high-pass filter
C. a bandpass filter
D. a band-stop filter
Ques.No.148. A noninverting closed-loop op-amp circuit generally has a gain factor:
A. less than one
B. greater than one
C. of zero
D. equal to one
Ques.No.149. Op-amps used as high- and low-pass filter circuits employ which
configuration?
A. noninverting B.
comparator
C. open-loop D.
inverting
Ques.No.150. An astable multivibrator is also known as a:
A. one-shot multivibrator
B. free-running multivibrator
C. bistable multivibrator
D. monostable multivibrator
Ques.No.151.With negative feedback, the returning signal:
A. aids the input signal
B. is proportional to output current
C. opposes the input signal
D. is proportional to differential voltage gain
Ques.No.152. What starts a free-running multivibrator?
A. a trigger
B. an input signal
C. an external circuit
D. nothing
Ques.No.153. A portion of the output that provides circuit stabilization is considered to
be:
A. negative feedback
B. distortion
C. open-loop
D. positive feedback
Ques.No.154. A circuit whose output is proportional to the difference between the input
signals is considered to be which type of amplifier?
A. common-mode B. darlington
C. differential D. operational
Ques.No.155. With negative feedback, the returning signal
A. is proportional to the output current
B. is proportional to the differential voltage gain
C. opposes the input signal
D. aids the input signal
Ques.No.156. The voltage follower has a:
A. closed-loop voltage gain of unity
B. small open-loop voltage gain
C. closed-loop bandwidth of zero
D. large closed-loop output impedance
Ques.No.157. The ratio between differential gain and common-mode gain is called:
A. amplitude
B. differential-mode rejection
C. common-mode rejection
D. phase
Ques.No.158. With a differential gain of 50,000 and a common-mode gain of 2, what is
the common-mode rejection ratio?
A. –87.9 dB
B. –43.9 dB
C. 43.9 dB
D. 87.9 dB
Ques.No.159. If the input to a comparator is a sine wave, the output is a:
A. ramp voltage
B. sine wave
C. rectangular wave
D. sawtooth wave
Ques.No.160. What three subcircuits does a phase locked loop (PLL) consist of?
A. phase comparator, comparator, and VCO
B. phase comparator, bandpass filter, and VCO
C. phase comparator, bandpass filter, and demodulator
D. phase comparator, low-pass filter, and VCO
Ques.No.161. The major difference between ground and virtual ground is that virtual
ground is only a:
A. voltage reference
B. current reference
C. power reference
D. difference reference
Ques.No.162. The Schmitt trigger is a two-state device that is used for:
A. pulse shaping
B. peak detection
C. input noise rejection
D. filtering
Ques.No.163. How many logic states does an S-R flip-flop have?
A. 2 B. 3
C. 4 D. 5
Ques.No.164. An ideal amplifier should have:
A. high input current
B. zero offset
C. high output impedance
D. moderate gain
Ques.No.165. What is the difference between common-mode and differential-mode input
signals?
A. phase relationship
B. voltage
C. current
D. apparent power
Ques.No.165. A circuit that uses an amplifier with passive filter elements is called a(n):
A. relaxation oscillator
B. signal generator
C. differential amplifier
D. active filter
Ques.No.166. The input offset current equals the
A. average of two base currents
B. collector current divided by the current gain
C. difference between two base-emitter voltages
D. difference between two base currents
8- BASIC OP-AMP CIRCUITS
1.
The center frequency of a band-pass filter is always equal to the A. bandwidth
B. –3 dB frequency
C. bandwidth divided by Q
D
.
geometric average of the critical frequencies
3. A zero-level detector is a A. comparator with a sine-wave output
B. comparator with a trip point referenced to zero
C. peak detector
D
.
limiter
4.A digital-to-analog converter is an application of the A. scaling adder
B. voltage-to-current converter
C. noninverting amplifier
D
.
adjustable bandwidth circuit
9- MEASURING INSTRUMENTS
1. What device is similar to an RTD but has a negative temperature coefficient? A. Strain gauge
B. Thermistor
C. Negative-type RTD
D. Thermocouple
2.The resistive change of a strain gauge A. is based on the weight placed upon it, but can be many thousands of ohms
B. is usually no more than 100
C. is based on the gauge factor, but is typically less than an ohm
D. has a positive temperature coefficient
3.The silicon-controlled rectifier can be turned off A. by a negative gate pulse
B. by forced commutation
C. with the off switch
D. when the breakover voltage is exceeded
4.The output voltage of a typical thermocouple is A. less than 100 mV
B. greater than 1 V
C. Thermocouples vary resistance, not voltage.
D. None of the above
7.Temperature sensing can be achieved by the use of A. thermocouples
B. RTDs
C. thermistors
D All of the above
12.Holding current for an SCR is best described as A. the minimum current required for turn-off
B. the current required before an SCR will turn on
C. the amount of current required to maintain conduction
D the gate current required to maintain conduction
1. A TRIAC: A. can trigger only on positive gate voltages
B. can trigger only on negative gate voltages
C. cannot be triggered with gate voltages
D. can be triggered by either a positive or a negative gate voltage
2. When checking a good SCR or TRIAC with an ohmmeter it will:
A. show high resistance in both directions
B.
show low resistance with positive on anode and negative on cathode, and high resistance when
reversed
C.
show high resistance with negative on anode and positive on cathode, and low resistance when
reversed
D. show low resistance in both directions
3. What does a hall effect sensor sense?
A. temperature
B. moisture
C. magnetic fields
D. pressure
4. What causes the piezoelectric effect?
A. heat or dissimilar metals
B. pressure on a crystal
C. water running on iron
D. a magnetic field
5. Which is the DIAC?
A.
B.
C.
D.
6. A UJT has:
A. two base leads
B. one emitter lead
C. two emitter leads and one base lead
D. one emitter lead and two base leads
7. The only way to close an SCR is with:
A. a trigger input applied to the gate
B. forward breakover voltage
C. low-current dropout
D. valley voltage
8. What is an SCR?
A. a PNPN thyristor with 3 terminals
B. a PNPN thyristor with 4 terminals
C. a PNP thyristor with 3 terminals
D. an NPN thyristor with 3 terminals
9. The only way to close an SCR is with:
A. a trigger input applied to the gate
B. forward breakover voltage
C. low-current dropout
D. valley voltage
10. What type of application would use a photovoltaic cell?
A. an automobile horn
B. a TI 92 calculator
C. a magnetic field detector
D. a remote power source
11. Which is the seven-segment display?
A.
B.
C.
D.
12. The smallest amount of current that the cathode-anode can have, and still sustain conduction of
an SCR is called the:
A. maximum forward current
B. maximum forward gate current
C. holding current
D. reverse gate leakage current
13. Once a DIAC is conducting, the only way to turn it off is with:
A. a positive gate voltage
B. a negative gate voltage
C. low-current dropout
D. breakover
14. Which is the TRIAC?
A.
B.
C.
D.
15. The DIAC is a:
A. transistor
B. unidirectional device
C. three-layer device
D. bidirectional device
16. What type of application would use an injection laser diode?
A. a 10BASE-T Ethernet
B. a liquid crystal display
C. a fiber optic transmission line
D. a good flashlight
17. The PUT (programmable unijunction transistor) is actually a type of:
A. UJT thyristor
B. FET device
C. TRIAC
D. SCR
18. A transducer's function is to:
A. transmit electrical energy
B. convert energy
C. produce mechanical energy
D. prevent current flow
10- Number Systems and Codes
1. Base 10 refers to which number system? A. binary coded decimal
B. decimal
C. octal
D. hexadecim
2. Convert the decimal number 151.75 to binary.
A. 10000111.11 B. 11010011.01
C. 00111100.00 D. 10010111.11
3. Convert the binary number 1011010 to hexadecimal.
A. 5B B. 5F
C. 5A D. 5C
4. The number of bits used to store a BCD digit is:
A. 8 B. 4
C. 1 D. 2
5. Sample-and-hold circuits in ADCs are designed to:
A. sample and hold the output of the binary counter during the conversion process
B. stabilize the ADCs threshold voltage during the conversion process
C. stabilize the input analog signal during the conversion process
D. sample and hold the ADC staircase waveform during the conversion process
6. The weight of the LSB as a binary number is:
A. 1 B. 2
C. 3 D. 4
7. What is the difference between binary coding and binary coded decimal?
A. Binary coding is pure binary.
B. BCD is pure binary.
C. Binary coding has a decimal format.
D. BCD has no decimal format.
8. Convert the binary number 1001.0010 to decimal.
A. 125 B. 12.5
C. 90.125 D. 9.125
9. Convert 110010012 (binary) to decimal.
A. 201 B. 2001
C. 20 D. 210
10. What is the decimal value of the hexadecimal number 777?
A. 191 B. 1911
C. 19 D. 19111
11. What is the resultant binary of the decimal problem 49 + 1 = ?
A. 01010101 B. 00110101
C. 00110010 D. 00110001
12. 3428 is the decimal value for which of the following binary coded decimal (BCD) groupings?
A. 11010001001000 B. 11010000101000
C. 011010010000010 D. 110100001101010
13. What is the result when a decimal 5238 is converted to base 16?
A. 327.375 B. 12166
C. 1388 D. 1476
11- DIGITAL ELECTRONICS
1. Which statement below best describes a Karnaugh map? A. It is simply a rearranged truth table.
B. The Karnaugh map eliminates the need for using NAND and NOR gates.
C. Variable complements can be eliminated by using Karnaugh maps.
D. A Karnaugh map can be used to replace Boolean rules.
2. Which of the examples below expresses the commutative law of multiplication?
A. A + B = B + A
B. A • B = B + A
C. A • (B • C) = (A • B) • C
D. A • B = B • A
3. The Boolean expression is logically equivalent to what single gate?
A. NAND B. NOR
C. AND D. OR
4. The observation that a bubbled input OR gate is interchangeable with a bubbled output AND gate is
referred to as:
A. a Karnaugh map
B. DeMorgan's second theorem
C. the commutative law of addition
D. the associative law of multiplication
5. The systematic reduction of logic circuits is accomplished by:
A. symbolic reduction
B. TTL logic
C. using Boolean algebra
D. using a truth table
6. Logically, the output of a NOR gate would have the same Boolean expression as a(n):
A. NAND gate immediately followed by an INVERTER
B. OR gate immediately followed by an INVERTER
C. AND gate immediately followed by an INVERTER
D. NOR gate immediately followed by an INVERTER
7. Which of the examples below expresses the distributive law of Boolean algebra?
A. A • (B • C) = (A • B) + C
B. A + (B + C) = (A • B) + (A • C)
C. A • (B + C) = (A • B) + (A • C)
D. (A + B) + C = A + (B + C)
8. Which output expression might indicate a product-of-sums circuit construction?
A.
B.
C.
D.
9. One of DeMorgan's theorems states that . Simply stated, this means that logically
there is no difference between:
A. a NAND gate and an AND gate with a bubbled output
B. a NOR gate and an AND gate with a bubbled output
C. a NOR gate and a NAND gate with a bubbled output
D. a NAND gate and an OR gate with a bubbled output
10. The commutative law of addition and multiplication indicates that:
A. the way we OR or AND two variables is unimportant because the result is the same
B. we can group variables in an AND or in an OR any way we want
C. an expression can be expanded by multiplying term by term just the same as in ordinary algebra
D.
the factoring of Boolean expressions requires the multiplication of product terms that contain like
variables
11. Which of the following expressions is in the sum-of-products (SOP) form?
A. Y = (A + B)(C + D)
B. Y = AB(CD)
C.
D.
1. How many inputs are required for a 1-of-10 BCD decoder? A. 4 B. 8
C. 10 D. 1
2. Most demultiplexers facilitate which of the following?
A. decimal to hexadecimal
B. single input, multiple outputs
C. ac to dc
D. odd parity to even parity
3. One application of a digital multiplexer is to facilitate:
A. code conversion
B. parity checking
C. parallel-to-serial data conversion
D. data generation
4. Select one of the following statements that best describes the parity method of error detection:
A. Parity checking is best suited for detecting single-bit errors in transmitted codes.
B.
Parity checking is best suited for detecting double-bit errors that occur during the transmission of
codes from one location to another.
C. Parity checking is not suitable for detecting single-bit errors in transmitted codes.
D. Parity checking is capable of detecting and correcting errors in transmitted codes.
5. A multiplexed display:
A. accepts data inputs from one line and passes this data to multiple output lines
B. uses one display to present two or more pieces of information
C. accepts data inputs from multiple lines and passes this data to multiple output lines
D. accepts data inputs from several lines and multiplexes this input data to four BCD lines
6. When two or more inputs are active simultaneously, the process is called:
A. first-in, first-out processing
B. priority encoding
C. ripple blanking
D. priority decoding
7. Which type of decoder will select one of sixteen outputs, depending on the 4-bit binary input
value?
A. hexadecimal
B. dual octal outputs
C. binary-to-hexadecimal
D. hexadecimal-to-binary
9. A circuit that responds to a specific set of signals to produce a related digital signal output is called
a(n):
A. BCD matrix
B. display driver
C. encoder
D. decoder
10. Which digital system translates coded characters into a more intelligible form?
A. encoder B. display
C. counter D. decoder
11. A basic multiplexer principle can be demonstrated through the use of a:
A. single-pole relay
B. DPDT switch
C. rotary switch
D. linear stepper
12. In a BCD-to-seven-segment converter, why must a code converter be utilized?
A. No conversion is necessary.
B. to convert the 4-bit BCD into gray code
C. to convert the 4-bit BCD into 10-bit code
D. to convert the 4-bit BCD into 7-bit code
1. A ripple counter's speed is limited by the propagation delay of: A. each flip-flop
B. all flip-flops and gates
C. the flip-flops only with gates
D. only circuit gates
2. To operate correctly, starting a ring counter requires:
A. clearing all the flip-flops
B. presetting one flip-flop and clearing all the others
C. clearing one flip-flop and presetting all the others
D. presetting all the flip-flops
3. What type of register would shift a complete binary number in one bit at a time and shift all the
stored bits out one bit at a time?
A. PIPO B. SISO
C. SIPO D. PISO
4. Synchronous counters eliminate the delay problems encountered with asynchronous (ripple)
counters because the:
A. input clock pulses are applied only to the first and last stages
B. input clock pulses are applied only to the last stage
C. input clock pulses are not used to activate any of the counter stages
D. input clock pulses are applied simultaneously to each stage
5. One of the major drawbacks to the use of asynchronous counters is that:
A. low-frequency applications are limited because of internal propagation delays
B. high-frequency applications are limited because of internal propagation delays
C.
Asynchronous counters do not have major drawbacks and are suitable for use in high- and low-
frequency counting applications.
D.
Asynchronous counters do not have propagation delays, which limits their use in high-frequency
applications.
6. Which type of device may be used to interface a parallel data format with external equipment's
serial format? A. key matrix
B. UART
C. memory chip
D. serial-in, parallel-out
8. A comparison between ring and johnson counters indicates that:
A. a ring counter has fewer flip-flops but requires more decoding circuitry
B. a ring counter has an inverted feedback path
C. a johnson counter has more flip-flops but less decoding circuitry
D. a johnson counter has an inverted feedback path
9. What type of register would shift a complete binary number in one bit at a time and shift all the
stored bits out one bit at a time?
A. parallel-in/parallel-out B. parallel-in/serial-out
C. serial-in/parallel-out D. serial-in/serial-out
10. A sequence of equally spaced timing pulses may be easily generated by which type of counter
circuit?
A. shift register sequencer
B. clock
C. johnson
D. binary
11. What is meant by parallel-loading the register?
A. Shifting the data in all flip-flops simultaneously
B. Loading data in two of the flip-flops
C. Loading data in all four flip-flops at the same time
D. Momentarily disabling the synchronous SET and RESET inputs
12. What is a shift register that will accept a parallel input and can shift data left or right called?
A. tri-state
B. end around
C. bidirectional universal
D. conversion
13. What happens to the parallel output word in an asynchronous binary down counter whenever a
clock pulse occurs?
A. The output word decreases by 1.
B. The output word decreases by 2.
C. The output word increases by 1.
D. The output word increases by 2.
14. Mod-6 and mod-12 counters are most commonly used in:
A. frequency counters
B. multiplexed displays
C. digital clocks
D. power consumption mete
1. A computerized self-diagnostic for a ROM test uses: A. the check-sum method
B. a ROM listing
C. ROM comparisons
D. a checkerboard test
2. How many storage locations are available when a memory device has twelve address lines?
A. 144 B. 512
C. 2048 D. 4096
3. Which of the following memories uses a MOSFET and a capacitor as its memory cell?
A. SRAM B. DRAM
C. ROM D. DROM
4. Which of the following best describes nonvolatile memory?
A. memory that retains stored information when electrical power is removed
B. memory that loses stored information when electrical power is removed
C. magnetic memory
D. nonmagnetic memory
5. The access time (tacc) of a memory IC is governed by the IC's:
A. internal address buffer
B. internal address decoder
C. volatility
D. internal address decoder and volati
6. Select the best description of read-only memory (ROM).
A. nonvolatile, used to store information that changes during system operation
B. nonvolatile, used to store information that does not change during system operation
C. volatile, used to store information that changes during system operation
D. volatile, used to store information that does not change during system operation
7. Advantage(s) of an EEPROM over an EPROM is (are):
A. the EPROM can be erased with ultraviolet light in much less time than an EEPROM
B. the EEPROM can be erased and reprogrammed without removal from the circuit
C. the EEPROM has the ability to erase and reprogram individual words
D. the EEPROM can erase and reprogram individual words without removal from the circuit
8. Which of the following RAM timing parameters determine(s) its operating speed?
A. tacc
B. taa and tacs
C. t1 and t3
D. trc and twc
9. Memory that loses its contents when power is lost is:
A. nonvolatile B. volatile
C. random D. static
10. Select the best description of the fusible-link PROM.
A. user programmable, one-time programmable
B. manufacturer programmable, one-time programmable
C. user programmable, reprogrammable
D. manufacturer programmable, reprogrammable
11. A nonvolatile type of memory that can be programmed and erased in sectors, rather than one
byte at a time is:
A. flash memory
B. EPROM
C. EEPROM
D. MPROM
12. Which of the following best describes static memory devices?
A. memory devices that are magnetic in nature and do not require constant refreshing
B. semiconductor memory devices in which stored data is retained as long as power is applied
C. memory devices that are magnetic in nature and require constant refreshing
D.
semiconductor memory devices in which stored data will not be retained with the power applied
unless constantly refreshed
13. What is the principal advantage of using address multiplexing with DRAM memory?
A. reduced memory access time
B. reduced requirement for constant refreshing of the memory contents
C. reduced pin count and decrease in package size
D. no requirement for a chip-select input line, thereby reducing the pin count
12- RADIO & TV ENGINEERING.
1. The noise generated by a resistor depends upon
A. its resistance value
B. its operating temperature
C. both its resistance value and operating temperature
D. none of the above
In a superheterodyne receiver
A. the IF stage has better selectivity than RF stage
B. the RF stage has better selectivity than IF stage
C. the RF stage has same selectivity than IF stage
D. none of the above
The function of an AM detector circuit is to
A. rectify the input signal
B. discard the carrier
C. provide audio signal
D. all of the above
Which of the following should be used in order to prevent overloading or the last IF amplifier
in a receiver?
A. Variable selectivity
B. Variable sensitivity
C. Double conversion
D. Squelch
Most popular IF for receivers tuning to 540 to 1650 kHz is
A. 433 kHz
B. 455 kHz
C. 545 kHz
D. 555 kHz
In a broadcast superheterodyne receiver
A. the local oscillator operates below the signal frequency
B. local oscillator frequency is normally double the IF
C. RF amplifier normally works at kHz above the carrier frequency
D. mixer input must be tuned to the signal frequency
A duplexer is a device used to
A. feed more than one receiver from a single antenna
B. connect two transmitters to the same antenna
C. connect a receiver and a transmitter to the same antenna
D. none of these
A heterodyne frequency changer is called a
A. Modulator
B. Mixer
C. Demodulator
D. Frequency translator
RF amplifiers are used in radio receivers for
A. improved image frequency rejection
B. improved rejection of adjacent unwanted signals
C. prevention of re-radiation of the local oscillator through the antenna of the receiver
D. all of the above
In a receiver, which of the following device has IF input but RF output?
A. Demodulator
B. Loudspeaker
C. Audio amplifier
D. Frequency changer
Transistor are free from which type of noise?
A. Resistance noise
B. Partition noise
C. Flicker noise
D. Shot noise
Standard AM radio broadcasts are confined to
A. MF B. HF
C. VHF D. UHF
A transmitter serial current contains
A. carrier frequencies
B. audio frequencies
C. radio frequencies
D. none of the above
In a broadcast superheterodynes receiver having no RF amplifier, the loaded Q of the antenna
coupling circuit is 100. If the intermediate frequency is 455 kHz. The image frequency at 25
MHz will be
A. 24.09 MHz
B. 24.54 MHz
C. 25.45 MHz
D. 25.91 MHz
In a communication system, noise is most likely to affect the signal
A. at the transmitter
B. in the channel
C. in the information source
D. at the destination
In a radio receiver, if the intermediate frequency is too high
A. Selectivity will be poor
B. Tracking difficulties will be least
C. Adjacent channel rejection will improve
D. All of the above will occur
In a superheterodyne receiver, the IF is 455 kHz. If it is tuned to kHz, the image frequency
will be
A. 1655 kHz
B. 2110 kHz
C. 745 kHz
D. 910 kHz
The selectivity of most receivers is determined largely by
A. sensitivity
B. characteristics of IF section
C. antenna direction
D. all of the above
In a superheterodyne receiver with an IF of 450 kHz is tuned to a signal at 1200 kHz. The
image frequency is
A. 750 kHz
B. 990 kHz
C. 1650 kHz
D. 2100 kHz
Padders are used in a receiver to
A. discard the carrier
B. facilitate tracking
C. filter the input signal
D. suppress noise
In a radio receiver, the local oscillator is tuned to a frequency
A. lower than the incoming frequency
B. higher than the incoming frequency
C. equal to incoming frequency
D. any of the above
Which of the following oscillator is generally not used at VHF?
A. Colpitts oscillator
B. Clapp oscillator
C. Armstrong oscillator
D. Ultra Audio oscillator
The output of a diode detector contains
A. D.C. voltage
B. modulating signal
C. RF ripple
D. all of the above
Which of the following noise does not occur in transistors?
A. Partition noise
B. Shot noise
C. Flicker noise
D. Resistance noise
Noise generated in a resistor is also known as
A. partition noise
B. white noise
C. thermal noise
D. shot noise
The selectivity of a radio receiver is
A. its ability to reject adjacent unwanted signals
B. its ability to amplify weak signals
C. the frequency at which it gives maximum amplification to signal.
D. its ability to suppress noise.
In superheterodyne receivers, the local oscillator is used to
A. detect the modulating signal
B. amplify the received modulated carrier
C. shift the frequency of the received modulated carrier to the IF band
Which of the following is same in AM and FM receivers?
A. Demodulator
B. AGC
C. IF amplifier
D. All of the above
1. Camera signal output without sync is called A. Black burst B. generator lock video C. composite video D. noncomposite video
2. When the TV set was turned on, full power was applied to the heater and the picture appeared within a fraction of a second.
A. Ultor B. Implosion C. Instant-on operation D. Screen persistence
3. What is the typical anode voltage for a 25-in color picture tube? A. 10 kV B. 30 kV C. 1 kV D. 30 V
4. Which of the following is TRUE? A. The diameter of the vidicon image plate is about 5 in. (127 mm) B. The plumbicon camera tube uses a silicon target plate.
C. The composite video signal includes the camera signal and sync but not blanking. D. the lens inverts the optical image on the faceplates of the camera tube.
5. A lens has an 8-cm focal and 4-cm diameter. Its f rating is A. 2 B. 4 C. 8 D. 32
6. The gamma o f the picture tube is A. 0.4545 B. 1.0 C. 1.4 D. 2.2
7. A typically value of vidicon dark current is A. 0.2 uA B. about 200 uA C. 8 mA D. 800 mA
8. What is the gamma required for the camera tube? A. 2.2 B. 0.4545 C. 4.545 D. 0.22
9. To how many lax units is the illuminator of 3 fs, approximately equal? A. 650 B. 225 C. 65 D. 30
10. Beam alignment magnets for the camera tube are adjusted while rocking which control? A. Optical focus B. Electrical focus C. Beam current D. Shading
11. In gamma correction the is stretched by the picture tube. A. Black B. gray C. white D. red
12. Precise scanning size and linearity are most important in A. a black-and-white camera B. a plumbicon C. a single-tube color pickup D. a saticon
13. Special effects and production switching are done by the A. CCU B. ENG camera C. SEG D. Sync generator
14. What is the usual heater voltage for picture tube? A. 1.6 v B. 5.6 V C. 6.3 V D. 9.3V
15. What is the diagonal screen size for the 19CP4 picture tube? A. 12 in. B. 16 in. C. 19 in. D. 24 in.
16. What are the phosphor numbers, respectively, for monochrome and color picture tubes? A. P1 and P4 B. P1 and P22 C. P4 and P22 D. P4 and P1
17. Which of the following is the most negative (or least positive) electrode is the electron gun? A. Cathode B. Control grid G1 C. Screen grid D. Focus grid
18. A low-contrast picture in which white seems flat and lacking in detail suggest A. low beam current B. high gain in the amplifier C. excessive gamma D. insufficient scanning width
19. The part of the visible spectrum where camera pickup tubes have the greatest output is A. red B. blue C. yellow-green D. infrared
20. If the camera cannot be placed far away enough to include everything in the scene, change the lens to one with a
A. lower f rating B. higher f rating C. longer focal length D. shorter focal length
21. To what deflection angle does a maximum deflection angle of 45 deg either side center correspond? A. 30º B. 90º C. 120º D. 360º
22. Typically, the anode capacitance for a 25-in tube is A. 2 B. 20 C. 205 D. 2000
23. What is the color of P1 screen phosphor? A. Red B. Blue C. White D. Green
24. Which of the following camera tubes has minimum lag? A. Vidicon B. Plumbicon C. Saticon D. Iconoscope
25. is more important for the gamma correction for the camera tube. A. Color B. Monochrome C. Both Color and monochrome D. Either of Color or monochrome
26. Which of the following is FALSE? A. The lens inverts the optical image on the faceplate of the camera tube. B. The composite video signal includes the camera signal and sync not blanking C. The standard composite video from a camera is 1V p-p with negative sync. D. The plumbicon uses a lead oxide layer for the target plate.
27. Which of the following produces the signal variations for G4 of the vidicon. A. Target plate B. Wire mesh C. Muzzle D. Beam control
28. Which of the following camera tube uses lead oxide (PbO) for the photoconductive target plate? A. Vidicon B. Plumbicon C. Saticon D. Image Orthicon
