Basic Electrical And Electronics 225 Important MCQ PDF

Answer have given by bold option.

Q.1.Electron-hole pair are produced by
(a) recombination (b) thermal energy (c) ionization (d)doping

Q.2.Recombination is when
(a) an electron falls into a hole
(b) a positive and a negative ion bond together
(c)a valence electron becomes a conduction electron
(d)a crystal is formed

Q.3.Each atom in a silicon crystal has
(a) four valence electrons
(b) four conduction electrons
(c) eight valence electrons, four of its own and four shared
(d)no valence electrons because all are shared with other atoms

Q.4.The current in a semiconductor is produced by
(a) electrons only (b) holes only (c) negative ions (d)both electrons and holes

Q.5.The process of adding an impurity to an intrinsic semiconductor is called
(a) doping (b) recombination (c)atomic modification (d)ionization

Q.6.A trivalent impurity is added to silicon to create
(a) germanium (b) a p-type semiconductor
(c) an n-type semiconductor (d) a depletion region

Q.7.The purpose of pentavalent impurity is to
(a) reduce the conductivity (b) increase the number of holes
(c) increase the number of free electrons (d)create minority carriers

Q.8.For a silicon diode, the value of the forward-bias voltage typically
(a) must be greater than 0.3V (b) must be greater than 0.7V
(c) depends on the width of depletion region (d)depends on the concentration of majority carriers

Q.9.When forward biased , a diode
(a) blocks current (b) conducts current
c) has a high resistance (d) drops a large voltage

Q.10.When a voltmeter is placed across a forward-biased diode, it will read a voltage approximately equal to
(a) the bias battery voltage (b) 0V
(c) the diode barrier potential (d) the total circuit voltage

Q.11.The term bias means
(a) the ration of majority carriers to minority carriers
(b) the amount of current across a diode
(c) a dc voltage is applied to control the operation of a device
(d) none of the above

Q.12.In a LED, the light is produced by a solid state process called as
(a) light radiation (b) electroluminescence (c) light multiplication (d) phospherence

Q.13.Efficiency of LED is given by
(a) light to light conversion (b) light to electrical conversion
(c) electrical power to visible light conversion (d) none of above

Q.14.The wavelength of the light emitted and its color depends on the
(a) forward voltage (b) forward current
(c) band gap energy of the material forming P-N junction (d) none of the above

Q.15.The material used for red LED is
(a) GaP (b) GaAsP (c) AlGaAs (d) Above all

Q.16.A silicon diode is in series with a 1.0 kΩ resistor and a 5V battery. If the anode is connected to the positive battery terminal, the cathode voltage with respect to the negative battery terminal is
(a) 0.7V (b) 0.3V (c) 5.7V (d) 4.3V

Q.17.Although current is blocked in reverse bias,
(a) there is some current due to majority carrier
(b) there is very small current due to minority carriers
(c) there is an avalanche current
(d) none of the above

Q.18.The average value of a half wave rectified voltage with a peak value of 200V is
(a) 63.7V (b) 127.3V (c) 141V (d) 0V

Q.19.When a 60Hz sinusoidal voltage is applied to the input of a half-wave rectifier, the output frequency is
(a) 120Hz (b) 30Hz (c) 60Hz (d) 0Hz

Q.20.The peak value of the input to a half-wave rectifier is 10V.The approximate peak value of the output is
(a) 10V (b) 3.18V (c) 10.7V (d) 9.3V

Q.21.The average value of full-wave rectified voltage with a peak value of 75V is
(a) 53V (b) 47.8V (c) 37.5V (d) 23.9V

Q.22.When a 60Hz sinusoidal voltage is applied to the input of a full-wave rectifier, the output frequency is
(a) 120Hz (b) 60Hz (c) 240Hz (d) 0Hz

Q.23.The total secondary voltage in a center-tapped full-wave rectifier is 125Vrms.Neglecting the diode drop, the rms output voltage is
(a) 125V (b) 177V (c) 100V (d) 62.5V

Q.24.When the peak output voltage is 100V,the PIV for each diode in a center-tapped full-wave rectifier is (neglecting the diode drop)
(a) 100V (b) 200V (c) 141V (d) 50V

Q.25.The ideal dc output voltage of a capacitor-input filter is equal to
(a) The peak value of the rectified voltage
(b) The average value of the rectified voltage
(c) The rms value of the rectified voltage
(d) None of the above

Q.26.If the load resistance of a capacitor-filtered full-wave rectifier is reduced, the ripple voltage
(a) increases (b) decreases (c) is not affected (d) has a different frequency

Q.27.If one of the diodes in a bridge full-wave rectifier opens, the output is approximately
(a) 0V (b) one-fourth the amplitude of the input voltage
(c) a half-wave rectified voltage (d) a 120Hz voltage

Q.28.The cathode of zener diode in a voltage regulator is normally
(a) more positive than the anode (b) more negative than the anode
(c) at +0.7 V (d) grounded

Q.29.If a certain zener diode has a zener voltage of 3.6V,it operates in
(a) regulated breakdown (b) Zener breakdown
(c) forward conduction (d) avalanche breakdown

Q.30.The data sheet for a particular zener gives VZ=10V at IZT=500mA.ZZ for these conditions is
(a) 50Ω (b) 20Ω (c) 10 Ω (d) unknown

Q.31.An LED
(a) emits light when reverse biased (b) senses light when reverse biased (c) emits light when forward biased (d) acts as a variable resistance

Q.32.When operated in cutoff and saturation, the transistor acts like
(a) a linear amplifier (b) a switch (c) a variable capacitor (d) a variable resistance

Q.33.In a voltage divider biased npn transistor, if the upper voltage-divider resistor(the one connected to VCC) opens,
(a) the transistor goes into cutoff (b) the transistor goes into saturation (c) the transistor burns out (d) the supply voltage is too high

Q.34.In a voltage divider biased npn transistor, if the lower voltage-divider resistor(the one connected to ground) opens,
(a) the transistor goes into cutoff (b) the transistor goes into saturation (c) the transistor burns out (d) the supply voltage is too high

Q.35.A certain common-emitter amplifier has a voltage gain of 100.If the emitter bypass capacitor is removed,
(a) The circuit will become unstable (b) the voltage gain will decrease (c) the voltage gain will increase (d) The Q-point will shift

Q.36.The JFET is
(a) a unipolar device (b) a voltage-controlled device
(c) a current controlled device (d) the supply voltage is too high

Q.37.The channel of JFET is between the
(a) gate and drain (b) drain and source (c) gate and source (d) input and output

Q.38.A JFET always operates with
(a) gate to source pn junction reverse-biased
(b) gate to source pn junction forward-biased
(c) the drain connected to ground
(d) the gate connected to source

Q.39.For VGS=0V,the drain current becomes constant when VDS exceeds
(a) cutoff (b) VDD (c) VP (d) 0V

Q.40.The constant-current area of a FET lies between
(a) cutoff and saturation (b) cutoff and pinch-off
(c) 0 and IDSS (d) pinch-off and breakdown

Q.41.For an oscillator to properly start, the gain around the feedback loop must initially be
(a) 1 (b) less than 1
(c) greater than 1 (d) equal to B

Q.42.IDSS is
(a) the drain current with the source shorted (b) the drain current at cutoff (c) the maximum possible drain current (d) the midpoint drain current

Q.43.Drain current in the constant-current area increases when
(a) the gate-to-source bias voltage decreases
(b) the gate-to-source bias voltage increases
(c) the drain to source voltage increases
(d) the drain to source voltage decreases

Q.44.At cutoff, the JFET channel is
(a) at its widest point
(b) completely closed by the depletion region
(c) extremely narrow
(d) reverse-biased

Q.45.A certain p-channel E-MOSFET has a VGS(th)=-2V.If VGS=0V,the drain current is
(a) 0A (b) ID(on) (c) maximum (d) IDSS

Q.46.A thyristor has
(a) two pn junctions (b) three pn junctions
(c)four pn junctions (d)only two terminals

Q.47.Common types of thyristors include
(a) BJTs and SCRs (b) UJTs and PUTs
(c)FETs and TRIACs (d)DIACs and TRIACs

Q.48.The specified value of holding current for an SCR means that
(a) the device will turn on when the anode current exceeds this value
(b) the device will turn off when the anode current falls below this value
(c) the device may be damaged if the anode current exceeds this value
(d) the gate current must equal or exceed this value to turn the device on

Q.49.The diac is
(a) a thyristor (b) a bilateral, two terminal device
(c) like two parallel 4-layer diodes in reverse directions (d)all of these

Q.50.The triac is
(a) like a bidirectional SCR (b) a four-terminal device
(c) not a thyristor (d) answers (a) and (b)

Q.51.An Integrated circuit (IC) op – amp has
(a)Two inputs and two outputs (b)one input and one output
(c)two inputs and one output (d)None of these

Q.52.Which of the following characteristics does not necessarily apply to an op-amp?
(a) High gain (b) low power
(c) high input impedance (d) low output impedance

Q.53.A differential amplifier
(a)Is part of an op –amp (b)Has one input and one output
(c)Has two outputs (d)Answers (a) and (c)

Q.54.When an op- amp is operated in the single – ended mode,
(a)the output is grounded (b)one input is grounded and a signal is applied to the other (c)both inputs are connected together (d)the output is not inverted

Q.55.In the differential mode,
(a) Opposite polarity signals are applied to the inputs (b) The gain is 1 (c) The outputs are different amplitudes (d) Only one supply voltage is used

Q.56.In the common mode,
( a) Both inputs are grounded (b) The outputs are connected together
(c) An identical signal appears on both inputs (d)The output signals are in phase

Q.57.Common – mode gain is
(a)Very high (b)Very low
(c)Always unity (d)Unpredictable

Q.58.If Av(d) = 3500 and Acm = 0.35, the CMRR is
(a) 1225 (b) 10,000 (c) 80 dB (d) Answer (b) and (c)

Q.59.With zero volts on both inputs, an op-amp ideally should have an output equal to
(a) The positive supply voltage (b) The negative supply voltage
(c) Zero (d) The CMRR

Q.60.Of the values listed, the most realistic value for open – loop gain of an op-amp is
(a) 1 (b)2000 (c)80dB (d)100,000

Q.61.A certain op-amp has bias currents of 50μA and 49.3 μA. The input offset current is
(a) 700nA (b) 99.3 μA (c) 49.7 μA (d) None of these

Q.62.The output of a particular op-amp increases 8 V in 12 μS. The slew rate is
(a) 96 V/ μS (b)0.67 V/ μS (c)1.5 V/ μS (d)None of these

Q.63.For an op-amp with negative feedback, the output is
(a) Equal to the input (b) Increased
(c) Fed back to the inverting input (d) Fed back to the non-inverting input

Q.64.The use of negative feedback
(a) Reduces the voltage gain of an op-amp (b) Makes the op-amp oscillate
(c) Makes linear operation possible (d) Answers (a) and (c)

Q.65.Negative feedback
(a) Increases the input and output impedance’s
(b) Increases the input impedance and the bandwidth
(c) Decreases the output impedance and the bandwidth
(d) Does not affect impedance’s or bandwidth

Q.66.A certain non-inverting amplifier has an Ri of 1.0 kΩ and an Rf of 100 kΩ. The closed-loop gain is
(a) 100,000 (b) 1000 (c) 101 (d) 100

Q.67.A certain inverting amplifier has a closed-loop gain of 25. The op-amp has an open-loop gain of 100,000. If another op-amp with an open-loop gain of 200,000 is substituted in the configuration, the closed-loop gain
(a)Doubles (b)Drops to 12.5 (c)Remains at 25 (d)Increases slightly

Q.68.A voltage-follower
(a) Has a gain of 1 (b) Is non-inverting (c) Has no feedback resistor (d) Has all of these

Q.69.The bandwidth of an ac amplifier having a lower critical frequency of 1 kHz and an upper critical frequency of 10 kHz is
(a)1 kHz (b)9 kHz (c)10 kHz (d)11 kHz

Q.70.Phase shift through an op-amp is caused by
(a)The internal RC circuits (b) The external RC circuits
(c)The gain roll-off (d)Negative feedback

Q.71.A summing amplifier can have
(a) Only one input (b) Only two inputs
(c) Any number of inputs (d) None of these

Q.72.If the voltage gain for each input of a summing amplifier with a 4.7 kΩ. feedback resistor is unity, the input resistors must have a value of
(a) 4.7 kΩ. (b) 4.7 kΩ. divided by the number of inputs
(c) 4.7 kΩ. times the number of inputs (d) 1

Q.73.In an integrator, the feedback element is a
(a) Resistor (b) Capacitor (c) Zener diode (d) Voltage divider

Q.74.For a step input, the output of an integrator is
(a) A pulse (b) A triangular wave (c) A spike (d) A Ramp

Q.75.The rate of change of integrator’s output voltage in response to a step input is set by
(a)The RC time constant (b)The amplitude of step input
(c)The current through the capacitor (d)All of these

Q.76.In a differentiator, the feedback element is
(a) Resistor (b) Capacitor (c) Zener diode (d) Voltage divider

Q.77.The output of differentiator is proportional to
(a)The RC time constant (b)The rate at which the input is changing
(c)The amplitude of the input (d)Answers (a) and (b)

Q.78.When you apply a triangular waveform to the input of a differentiator, the output is
(a)A dc level (b)An inverted triangular waveform
(c)A square waveform (d)The first harmonic of the triangular waveform

Q.79.An oscillator differs from an amplifier because
(a)It has more gain (b)It requires no input signal
(c)It requires no dc supply (d)It always has the same output

Q.80.Wein bridge oscillator are based on
(a) Positive feedback (b) Negative feedback
(c) The piezoelectric effect (d) High gain

Q.81.One condition for oscillation is
(a) A phase shift around the feedback loop of 180
(b) A gain around the feedback loop of one-third
(c) A phase shift around the feedback loop of 0
(d) A gain around the feedback loop of less than 1

Q.82.In a Wein –bridge oscillator, if the resistance in the positive feedback circuit are decreased, the frequency
(a)Decreases (b)Increases
(c)Remains same (d)None of these

Q.83.The Wein –bridge oscillator’s positive feedback circuit is
(a) An RL circuit (b) An LC circuit
(c) a voltage divider (d) a lead – lag circuit

Q.84.A phase shift oscillator has
(a) Three RC circuits (b) Three LC circuit
(c) A T- type circuit (d) A π- type circuit

Q.85.The operation of a relaxation oscillator is based on
(a) The charging and discharging of a capacitor
(b) A highly selective resonant circuit
(c)A very stable supply voltage
(d)Low power consumption

Q.86.One of the following generations of IC contained hundreds of transistors on each chip.
(a) MSI (b) SSI (c) LSI (d) VLSI

Q.87.One of the following generations of IC contained tens of thousands of transistors.
(a) MSI (b) SSI (c) LSI (d) VLSI

Q.88.Which of the following logic circuit takes data from a single source and distributes it to one Of several output lines?
(a) multiplexer (b) demultiplexer (c) encoder (d) decoder

Q.89.Which logic device is called distributor?
(a) demultiplexer (b) multiplexer (c) encoder (d) decoder

Q.90.A demultiplexer with 4-bit select input has
(a) one data input and four data output lines
(b) one data input and eight data output lines
(c) one data input and ten data output lines
(d) one data input and sixteen data output lines

Q.91.A combinational logic circuit which is used to send data coming from a single source to two or more separate destinations is called
(a) decoder (b) encoder (c) multiplexer (d) demultiplexer

Q.92.A flip-flop has two outputs which are
(a) always zero (b) always one
(c) always complementary (d) all of the above

Q.93.A flip-flop can be made using
(a) basic gates such as AND, OR and NOT
(b) NAND gates
(c) NOR gates
(d) any of above

Q.94.A flip-flip can store
(a) one bit of data (b) two bits of data
(c) three bits of data (d) any number of bits of data

Q.95.A sequential logic circuit consists of
(a) only flip-flops
(b) only gates
(c) flip-flops and combination logic circuits
(d) only combinational logic circuits

Q.96.A+B=B+A; AB=BA represent which laws
(a) Commutative
(b) Associative
(c) Distributive
(d) Idempotence

Q.99.The output of a logic gate is 1 when all its inputs are at logic 1, the gate is either
(a) A NAND or a NOR
(b) An AND or an OR
(c) An OR or an X-OR
(d) An AND or a NOR

Q.100.The output of a logic gate is 1 when all its inputs are at logic 0. The gate is either
(a) A NAND or a NOR
(b) An AND or an X-OR
(c) An OR or a NAND
(d) An X-OR or an X-NOR

Q.101.The most suitable gate to check whether the number of 1’s in a digital word is even or odd is
(a) X-OR (b) NAND (c) NOR (d) AND, OR and NOT

Q.102.The number of rows in the truth table of a 4- input gate is,
(a) 4 (b) 8 (c) 12 (d) 16

Q.103.For checking the parity of a digital word, it is preferable to use
(a) AND gates (b) NAND gates (c) X-OR gates (d) NOR gates

Q.104.A+AB+ABC+ABCD+ABCDE…. =
(a) 1 (b) A (c) A+AB (d) AB

Q.108.LVDT is a ….
(a) capacitive transducer (b) resistive transducer
(c) inductive transducer (d) none of them

Q.109.Thermocouples are ……….. transducers.
(a) active (b) passive (c) adhesive (d) both (a) and (c)

Q.110.A resistance thermometer is basically a/an
(a) active transducer (b) passive transducer
(c) potentiometer (d) none of these

Q.111.Platinum resistance thermometer can be used up to
(a) 200°C (b) 850°C (c) 1200°C (d) 1500°C

Q.112.Bourdon tubes have the advantages of
(a) high accuracy and good dynamic response
(b) high sensitivity and good repeatability
(c) not being prone to shock vibrations
(d) not being susceptible to hysteresis

Q.113.A transducer is basically a device which converts
(a) mechanical energy into electrical
(b) energy or information from one form to another
(c) mechanical displacement into electrical
(d) none of these

Q.114.The gauge factor of a strain gauge is given as
(a) G=ΔR/R/ Δl/l (b) G=Δl/l / ΔR/R
(c) G= ΔR/R/ ΔD/D (d) none of these

Q.115.Thermocouples are generally used for accurate temperature measurement up to
(a) 350°C (b) 550°C (c) 1400°C (d) 3500°C

Q.116.The principle of operation of LVDT is based on variation of
(a) self inductance (b) mutual inductance
(c) reluctance (d) permeance

Q.117.Self generating transducers are ………transducers.
(a) active (b) passive (c) secondary (d) inverse

Q.118.The transducer that converts the input signal into the output signal, which is a continuous function of time, is known as …………transducer.
(a) active (b) analog (c) passive (d) digital

Q.119.In semiconductor strain gauges, the change in resistance on application of strain is mainly on account of change in
(a) length of wire (b) diameter of wire
(c) resistivity (d) both (a) and (b)

Q.120.The drawback of semiconductor strain gauges are
(a) low fatigue life (b) poor linearity
(c) that they are expensive and brittle (d) none of these

Q.121.A strain gauge is a passive transducer and is employed for converting
(a) mechanical displacement into a change of resistance
(b) pressure into a change of resistance
(c) force into displacement
(d) none of the above

Q.122.Bonded strain gauges are
(a) exclusively used for construction of transducers
(b) exclusively used for stress analysis
(c) used for both stress analysis and construction of transducers
(d) none of the above

Q.123.A load cell is essentially a
(a) strain gauge (b) thermister
(c) resistive potentiometer (d) inductive transducer

Q.124.A load cell is an electro-mechanical device and is widely used for measurement of
(a) static forces (b) dynamic forces (c) temperature (d) both (a) and (b)

Q.125.Which of the following can be used for pressure measurement?
(a) Thermometer (b) pyrometer (c) Bolometer (d) Piezoelectric crystal

Q.126.Which of the following devices cannot be used for measurement of temperature?
(a) RTD (b) Thermocouple (c) LVDT (d) Pyrometer

Q.127.The transducers used for measurement of linear displacement are
(a) strain gauges and resistive potentiometers
(b) LVDTs, capacitive transducers and Hall effect transducers
(c) thermocouples, thermistes and RTDs
(d) both (b) and (c)

Q.128.Which of the following additional is required for measuring pressure with piezoelectric crystal?
(a) Bellows (b) strain gauges (c) Rotameter (d) RTD

Q.129.Transducer is classified on the basis of
(a) Transduction form used (b) cost (c) performance (d) compitability

Q.130.Resistive type of transducer converts the physical quantity into
(a) equivalent electrical signal (b) equivalent Resistance
(c) Digital signal (d) Low noise digital signal

Q.131.As temperature increases, if resistance increases then device is having
(a) NTC (b) PTC (c) STC (d) ETC

Q.132.As temperature increases, if resistance decreases then device is having
(a) STC (b) PTC (c) NTC (d) ETC

Q.133.Thermisters are basically known as
(a) Thermal resistor (b) Opto-thermal resistor
(c) Thermal detector (d) Temperature detector

Q.134.Working principle of a thermocouple depends upon
(a) Thermoelectric effect (b) piezoelectric effect
(c) Thermoresistive effect (d) Skin effect

Q.135.Following material used in K-type thermocouple
(a) Iron-constantan (b) Chromel-Alumel
(c) Chromel-constatan (d) Copper- constantan

Q.136.Bonded strain gauge is useful for measuring
(a) very small displacement (b) very large displacement
(c) medium displacement (d) any displacement

Q.137.Following is the type of Diaphragm
(a) Flat (b) Spherical (c) Spiral (d) Helical

Q.138.Following is the block used in Electronic weighing machine
(a) Load cell (b) Amplifier (c) Filter (d) above all

Q.139.Following is the ideal solution for the remote measurement application
(a) 1 wire transmitter (b) 2 wire transmitter
(c) 3 wire transmitter (d) 4 wire transmitter

Q.140.In two wire transmitter the output current range used is
(a) 4 mA- 40 mA (b) 4 mA – 50 mA
(c) 4 mA – 20mA (d) 4 mA – 50 mA

Q.141.Following is drawback of two wire transmitter
(a) potential difference exists between any two distant points along the earth’s surface
(b) Error signal will get introduced which is called as ground loop signal
(c) Isolation system between two wires is required
(d) above all

Q.142.Data logger does the following accurately and quickly
(a) measure and record the data (b) receive and transmits the data
(c) receives and process the data (d) process the data and transmits it

Q.143.Following is a function of signal conditioner used in data logger
(a) amplifier or attenuator (b) filter
(c) Linearizer (d) above all

Q.144.The CNC stands for
(a) computerized Normalization control (b) Controller based Numerical control
(c) computerized Numerical Control (d) computerized Numerical and logical control

Q.145.PLC is basically developed to operate as product
(a) based on sequence of events (b) based on parallel events
(c) based on antiparallel simultaneous events (d) None of above

Q.146.In P-controller the output of controller is
(a) proportional to the error
(b) Inversely proportional to the error
(c) directly proportional to the DC supply voltage
(d) Inversely proportional to the DC supply voltage

Q.147.PID controller is basically a
(a) Proportional controller (b) Integral controller
(c) Derivative controller (d) combination of all above

Q.148.Alarm annunciator is associated with following
(a) Medium temperature measurement and control system
(b) High temperature measurement and control system
(c) Pressure measurement and control system
(d) above all

Q.149.Communication is the transfer of meaningful information from
(a) source to destination (b) transmitter to receiver
(c) sender to receiver (d) above all

Q.150.The basic process of information exchange between transmitter and receiver is known as…..
(a) communication (b) controlling (c) signaling (d) modulating

Q.151.The process of converting electrical equivalent of the information to a suitable form is done by….
(a) transmitter (b) receiver (c) medium (d) above all

Q.152.The communication system with wire as conducting medium is known as ……
(a) wired communication (b) line communication
(c) guided media communication (d) above all

Q.153.The communication system which has no wires as conducting medium is known as…..
(a) wireless communication (b) radio communication
(c) unguided communication (d) above all

Q.154.Noise is basically a……
(a) random signal (b) unwanted electrical signal
(c) disturbance signal (d) above all

Q.155.The Voice Frequency (VF) range is ….
(a) 30 Hz to 300 Hz (b) 300 Hz to 3 kHz
(c) 3 kHz to 30 kHz (d) 9 kHz to 540 kHz

Q.156.The AM radio broadcast range is……..
(a) 30 kHz to 300kHz (b) 300 kHz to 3000 kHz
(c) 540 kHz to 1630 kHz (d) 1610 kHz to 1690 kHz

Q.157.Radio navigation and Aeronautical mobile frequency range is…..
(a) 30 Hz to 300 Hz (b) 300 Hz to 3 kHz
(c) 3 kHz to 30 kHz (d) 9 kHz to 540 kHz

Q.158.FM radio broadcast band frequency range is…
(a) 88MHz to 108 MHz (b) 216 MHz to 600 MHz
(c) 300 MHz to 3000 MHz (d) 470 MHz to 806 MHz

Q.159.The ultra High Frequency (UHF) range is…..
(a) 88 MHz to 174 MHz (b) 174 MHz to 216 MHz
(c) 216 MHz to 600 MHz (d) 300 MHz to 3000 MHz

Q.160.Following is the main advantage of twisted pair cable
(a) Simple in construction
(b) Cancellation of EMI pick-up from neighbour wire
(c) Cross talk is minimized
(d) Above all

Q.161.The RG-11 cable is used for following application
(a) Computer communication (b) PSTN- telephone link
(c) EPABX to telephone link (d) Undersea application

Q.162.The RG-59 cable is having following impedance
(a) 50 Ω (b) 59 Ω (c) 75 Ω (d) 100 Ω

Q.163.Optical fiber cable carries following
(a) Electrical signal (b) Light signal
(c) Sound signal (d) None of above

Q.164.The function of cladding in fiber cable is……
(a) to reflect the light back into core
(b) to reflect the light into silica coating
(c) to reflect the scattered light into coated strengthening fibers
(d) to reflect the light into cable jacket

Q.165.Refractive index of core in fiber cable compared to cladding is
(a) high (b) low (c) equal (d) extremely low

Q.166.The process of varying amplitude of sine wave carrier signal according to the instantaneous voltage of sine wave modulating signal is known as ….
(a) Ask (b) Amplitude- Phase modulation
(c) Amplitude modulation (d) PAM

Q.167.Bandwidth supported by coaxial cable is……
(a) 3 to 4 MHz (b) 300 to 400 MHz
(c) 2 to 3 GHz (d) none of above

Q.168.The cable RG-223 is used for …..
(a) broadcast communication (b) CCTV application
(c) TV application (d) UTP cable

Q.169.PSTN analog telephone system is example of…
(a) microwave communication (b) wired communication
(c) radio communication (d) satellite communication

Q.170.The modulation index factor is the rate of…..
(a) fc/fm (b) fm/fc (c) Em/Ec (d) Ec/Em

Q.171.The loss of information in AM wave is known as…
(a) under modulation (b) over modulation
(c) attenuation (d) rectification

Q.172.Following is the main drawback of TRF AM receiver
(a) Instability arising due to RF amplifiers with very high gain
(b) Variations in bandwidth over the tuning range
(c) Poor selectivity at high frequency
(d) Above all

Q.173.The Intermediate Frequency (IF) of AM receiver is…
(a) 455 MHz (b) 455 kHz (c) 10.7 MHz (d) 10.7 kHz

Q.174.IF amplifier used in AM receiver is basically a…
(a) wideband amplifier (b) narrowband amplifier
(c) R-C coupled amplifier (d) direct coupled amplifier

Q.175.The modulation index corresponding to maximum deviation and maximum modulating frequency is called as…
(a) modulation index (b) deviation ratio
(c) pre-emphasis factor (d) de- emphasis factor

Q.176.In mobile communication system, in every hexagonal cell following is used
(a) Base station (b) MTSO (Mobile Telephone Switching Office)
(c) Wi-Fi transmitter station (d) None of above

Q.177.The connection between hexagonal cells and PSTN is handled by….
(a) mobile phone (b) base station
(c) MTSO section (d) none of above

Q.178.In cellular transmitter system, the carrier generated by frequency synthesizer uses following modulation by the amplified voice signal from microphone
(a) Frequency modulation (b) Phase modulation
(c) AM modulation (d) None of above

Q.179.In the non-inverting amplifier if the feedback resistor is open, the voltage gain
(a) Increases (b) Decreases
(c) is not affected (d) depend on Ri

Q.180.A certain non-inverting amplifier has an R1=1KΩ and an Rf=100KΩ. The closed loop gain is
(a)100,000 (b) 1000 (c) 101 (d) 100

Q.181.An ideal Op-Amp has
(a)Infinite Av (b) infinite Ri
(c) Zero Ro (d) All the above

Q.182.For IC 741 typical value of input bias current is—————-
(a) 10μA (b) 80nA (c) 1mA (d) 30mA

Q.183.For IC 741 typical value of input offset current is—————-
(a)10μA (b) 20nA (c) 1mA (d) 30mA

Q.184.For IC 741 typical value of input offset voltage is—————-
(a) 2mV (b) 100mV (c) 50mV (d) 0.2V

Q.185.For IC 741 typical value of CMRR is—————-
(a) 90dB (b) 120dB (c) 150dB (d) 200dB

Q.186.For an three input inverting summing amplifier, Vout=-(V1+V2+V3)/3, What is the relation between Rf & R?
(a) R=3Rf (b) Rf=3R (c) R=0.3Rf (d) Rf=0.3R

Q.187.For an three input inverting summing amplifier, Vout= 3 * (V1+V2+V3), What is the relation between Rf & R?
(a) R=3Rf (b) Rf=3R (c) R=0.3Rf (d) Rf=0.3R

Q.188.In common cathode seven segment LED display to display digit 1 the data input to segment is
(Assume 0=Ground,1=+5V)
(a) a=1,b=0,c=0,d=0,e=0,f=0,g=0 (b) a=0,b=1,c=1,d=0,e=0,f=0,g=0
(c) a=1,b=0,c=0,d=1,e=1,f=1,g=1 (d) a=0,b=0,c=0,d=0,e=1,f=1,g=0

Q.189.If the value of maximum power dissipation of zener diode is 1W with the zener voltage of 8V. The maximum value of zener current is
(a) 125mA (b) 130mA (c) 330mA (d) 100mA

Q.190.For a certain 12V Zener diode, a 10mA change in zener current produces 0.1V change in Zener voltage. The Zener impedance is
(a) 1Ω (b) 100Ω (c) 10 Ω (d) 0.1 Ω

Q.191.Compared to a visible red LED, an infrared LED
(a) produces light with shorter wavelengths (b) produces light with all wavelengths
(c) produces only one color of light (d) produces light with longer wavelengths

Q.192.If you are checking a 60Hz full wave bridge rectifier and observe that the output has a 60Hz ripple.
(a) the circuit is working properly (b) there is an open diode
(c) the transformer secondary is shorted (d) the filter capacitor is leaky

Q.193.A 60V peak full wave rectified voltage is applied to a capacitor input filter. If f=120Hz, RL=10KΩ and C=10μF, the ripple voltage is
(a) 0.6V (b) 6mV (c) 5V (d) 2.88V

Q.194.A certain power supply filter produces an output with a ripple of 100mV peak to peak and dc value of 20V. The ripple factor is
(a) 0.05 (b) 0.005 (c) 0.00005 (d) 0.02

Q.195.When the rms output voltage of a bridge wave rectifier is 20V, the PIV across diode is
(a) 20V (b) 40V (c) 28.3V (d) 56.6V

Q.196.Reverse saturation current in silicon PN junction diode nearly doubles for every
(a) 20°C rise in temperature (b) 50°C rise in temperature
(c) 60°C rise in temperature (d) 10°C rise in temperature

Q.197.GaAs, LED emits radiation in the
(a) UV region (b) Blue color
(c) visible region (d) infra-red region

Q.198.The ripple factor of bridge rectifier is
(a) 0.482 (b) 0.812 (c) 1.11 (d) 1.21

Q.199.The basic purpose of filter is to
(a) minimize variations in a.c. input signal (b) suppress harmonics in rectified output
(c) removes ripples from rectifier output (d) stabilize dc output voltage

Q.200.If Vm is the peak value of an applied voltage in half wave rectifier with a large capacitor across load, then PIV is
(a) Vm/2 (b) Vm (c) 2Vm (d) 1.414Vm

Q.201.if, by mistake ac source in a bridge rectifier is connected across the dc terminals it will burn out and hence short___________diodes
(a) One (b) Two (c) Three (d) Four

Q.202.if the input supply frequency is 50Hz, the output supply frequency of a bridge wave rectifier is____________Hz
(a) 100 (b) 75 (c) 50 (d) 25

Q.203.When the PN junction diode is forward biased WWW.ALLEXAMREVIEW.COM
(a) the only current is hole current
(b) the only current is electron current
(c) the only current is produced by majority carriers
(d) the current is produced by both holes and electrons

Q.204.A voltage regulator is a circuit which
(a) Converts ac voltage to dc voltage
(b) Smoothens the ac variation in dc output voltage
(c) Maintain a constant dc output voltage in spite of the fluctuations in ac input voltage or load current
(d) None of above

Q.205.A bridge wave rectifier is preferable to an ordinary two diode full wave rectifier because
(a) it need much smaller transformer for the same output
(b) it uses four diode
(c) its transformer does not require center tap
(d) All the above

Q.206.For 1N4736 Zener diode has Zz=3.5 Ω. The datasheet gives Vzt=6.8V at Izt=37mA, What is voltage across zener terminals when the current is 50mA?
(a) 6.85V (b) 7.85V (c) 8.85V (d) 9.95V

Q.207.A Si PN junction has a reverse saturation current of I0=30nA at room temperature, the junction forward voltage required to produce current of 0.1mA is
(a) 0.42V (b) 0.55V (c) 0.80V (d) 0.49V

Q.208.Which rectifier requires four diodes
(a) half wave voltage doubler (b) full wave voltage doubler
(c) full wave bridge circuit (d) voltage quadrupler

Q.209.Junction breakdown of a PN junction occurs
(a) with forward bias (b) with reverse bias
(c) because of manufacturing defect (d) None of above

Q.210.A PN junction diodes dynamic conductance is directly proportional to
(a) the applied voltage (b) temperature
(c) the current (d) the thermal voltage

Q.211.In a full wave rectifier, the current in each of the diodes flows for
(a) complete cycle of the input signal
(b) half cycle of the input signal
(c) less than half of the input signal
(d) None of above

Q.212.The value of reverse bias resistance for an ideal diode is __________
(a) infinity (b) o (c) one (d) none of the above

Q.213.Device convert ac to dc is called _______________
(a) transformer (b) rectifier (c) inverter (d) none of the above

Q.214.Difference amp. is also known as ____________
(a) substractor (b) adder (c) divider (d) multiplier

Q.215.A capacitor offers ___________ reactance to dc
(a) Infinite (b) finite (c) 50% (d) None WWW.ALLEXAMREVIEW.COM

Q.216.Semiconductor material have __________ temp. coefficient
(a) Positive (b) Negative
(c) Both positive and negative (d) None

Q.217.A zener diode works on the principal of
(a) tunneling of charge carriers across junction
(b) thermionic emission
(c) diffusion of charge carriers across junction
(d) hopping of charge carriers across junction

Q.218.A dot matrix is a ____________________
(a) 2-dimensional array of dots (b) 3-dimensional array of dots
(c) 4-dimensional array of dots (d) 5-dimensional array of dots

Q.219.The applied input ac power to a half wave rectifier is 100 watts. The d.c output power obtained is 40 watts. What is the rectification efficiency?
(a)10% (b)20% (c)30% (d)40%

Q.220.if the ac input to a half rectifier has an rms value of 400/√2 volts, then diode PIV rating is
(a)200V (b)400V (c)300V (d)200V

Q.221.A half wave rectifier has an input voltage of 240 V rms if the step down transformer has turns ratio of 8:1, what is the load voltage?
(a)27.5v (b)86.5v (c)30v (d)42.5V

Q.222.A crystal diode having internal resistance of 20 ohm is used for half wave rectification. If the applied voltage is 50sinwt and load resistance = 800 ohm, find the d.c. Output voltage?
(a) 15.52 V (b) 10.52V (c) 23.52V (d) none

Q.223.A power supply A delivers 10V dc with ripple of 0.5V rms. While the power supply B delivers 25V dc with a ripple of 1 mVrms. Which is better power supply?
(a) Supply A (b) Supply B (c) both same (d) none

Q.224.In a certain oscillator, Av=50. The attenuation of the feedback circuit must be
(a) 1 (b) 0.01 (c) 10 (d) 0.02

Q.225.For an oscillator to properly start, the gain around the feedback loop must initially be
(a) 1 (b) less than 1
(c) greater than 1 (d) equal to B

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Power Electronics Special MCQ Part One
SIGNAL AND SYSTEM 50 MOST IMPORTANT EXPECTED MCQ WITH SOLUTION FOR VIZAG MT AND BEL PE EXAM 2017

12 Comments

  1. anu January 19, 2018
    • Harikesh Yadav January 19, 2018
  2. rahul banswar January 19, 2018
    • Harikesh Yadav January 19, 2018
  3. SOURAV January 20, 2018
    • Harikesh Yadav January 20, 2018
      • SOURAV January 21, 2018
        • Harikesh Yadav January 22, 2018
  4. sanket January 24, 2018
    • Harikesh Yadav January 25, 2018
      • anil kumar January 26, 2018
        • Harikesh Yadav January 27, 2018

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