SSC Scientific Assistant (IMD) Exam : Held on 24 Nov 2017 Shift-2

(Electronics)

QID : 1101 - A copper wire is 3 meter long and has a uniform cross-section of 0.6 square mm. At room temperature, the resistance of the wire is 0.183 ohms. What is the resistivity of the material?

Options:
1) 3.06 x 10-8 Ωm
2) 3.66 x 10-8 Ωm
3) 3.26 x 10-4 Ωm
4) 3.23 x 10-6 Ωm
Correct Answer: 3.66 x 10-8 Ωm
 
QID : 1102 - In order to cover a large area of a dielectric medium, the capacitance should be _______.

Options:
1) Very high
2) Low
3) Zero
4) Extremely low
Correct Answer: Very high

QID : 1103 - An LED made using GaP emits radiation in _______.

Options:
1) Visible region
2) Ultraviolet region
3) Infrared region
4) Green radiation
Correct Answer: Green radiation
 
QID : 1104 - What type of chemical bonding is present in a germanium semiconductor ?

Options:
1) Metallic
2) Covalent
3) Chemical
4) Ionic
Correct Answer: Covalent
 
QID : 1105 - Which capacitor has the maximum capacitance per unit volume?

Options:
1) Air capacitor
2) Mica capacitor
3) Ceramic capacitor
4) Electrolytic capacitor
Correct Answer: Electrolytic capacitor

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QID : 1106 - Consider the following semiconductor diodes:

(i). Germanium diode
(ii). Silicon diode
(iii). Schottky diode
(iv). Tunnel diode
The correct sequence of forward voltage drop in the decreasing order is:

Options:
1) 1,3,2,4
2) 1,2,3,4
3) 3,4,2,1
4) 2,3,1,4
Correct Answer: 2,3,1,4
 
QID : 1107 - 

Options:
1) 0.5 W

2) 1 W

3) 3.125 W

4) 3 W
Correct Answer: 3.125 W
 
QID : 1108 - A diode when connected in series with the output, then the circuit is called ______.

Options:
1) Limiter 
2) Series clipper
3) Parallel Clipper
4) IC voltage regulator
Correct Answer: Series clipper

QID : 1109 - A device is referred to as the linear device when the graph between the current and voltage across the device is a _____ .

Options:
1) Exponential
2) Non-exponential
3) Straight line
4) Constant
Correct Answer: Straight line
 
QID : 1110 - Calculate the hall voltage when the magnetic field is 8 A/m, current is 4 A, width is 5 m and the concentration of carrier is 100000.

Options:
1) 4.125 V
2) 0.3125 V
3) 4.2 V
4) 0.4 V
Correct Answer: 0.4 V
 
QID : 1111 - Using which diode in a regulated power supply, the unregulated input voltage as compared to the regulated output voltage will be larger?

Options:
1) Photo diode
2) p-n junction diode
3) Zener diode
4) Gunn diode
Correct Answer: Zener diode

QID : 1112 - Which region covers the highest area in a transistor?

Options:
1) Emitter
2) Collector
3) Base
4) Base-emitter
Correct Answer: Collector
 
QID : 1113 - What is the region of operation of the bipolar junction transistor (BJT) where both the junctions are in forward biased?

Options:
1) Active region
2) Ohmic region
3) Saturation region
4) Cut-off
Correct Answer: Saturation region

QID : 1114 - Which among the following are the disadvantages of FET over BJT:
i. It has high input resistance
ii. It has a large bandwidth
iii. It is more noisy
iv. It only allows the flow of majority charge carriers

Options:
1) 1 and 3
2) 2 and 4
3) 3 and 2
4) 4 only
Correct Answer: 4 only
 
QID : 1115 - Which circuit takes the less chip area in large scale integration?

Options:
1) TTL logic circuits
2) Bipolar circuits
3) High power circuits
4) CMOS circuits
Correct Answer: CMOS circuits
 
QID : 1116 - 

 

Options:
1) 15.00Ω
2) 47.23Ω
3) 1kΩ
4) 78.12Ω
Correct Answer: 78.12Ω
 
QID : 1117 - Consider the following:

i. MOSFET can be used as a voltage controlled capacitor.
ii. MOSFET can be used both as a voltage and a current controlled inductor.

Options:
1) (i) is True but (ii) is False
2) (ii) is True but (i) is False
3) Only (i) is true.
4) Both (i) and (ii) are True
Correct Answer: Only (i) is true.

QID : 1118 - The voltage gain of an amplifier without feedback and with negative feedback are 140 and 30 respectively. The percentage of negative feedback (beta) is:

Options:
1) 3%
2) 4%
3) 5%
4) 2%
Correct Answer: 3%
 
QID : 1119 - What are the properties of a power amplifier that are to be considered while designing a good power amplifier circuit?

Options:
1) Distortion, gain and bias stabilization
2) Frequency response
3) Sensitivity
4) All options are correct
Correct Answer: Distortion, gain and bias stabilization
 
QID : 1120 - A tuned amplifier has a peak output of 9 MHz and quality factor of 90. What is the bandwidth of the tuned amplifier?

Options:
1) 100 MHz
2) 100 kHz
3) 5.4 MHz
4) 6.05 MHz
Correct Answer: 100 kHz
 
QID : 1121 - A common emitter transistor amplifier has a collector load of 40 k-Ω, voltage gain is 400 and input resistance is 2 k-Ω. Calculate the value of voltage amplification of the amplifier.

Options:
1) 500
2) 2000
3) 8000
4) 7500
Correct Answer: 8000

QID : 1122 - Determine the number of different node pair voltages for a network with 9 nodes and 18 branches.

Options:
1) 7

2) 10

3) 45

4) 36
Correct Answer: 36
 
QID : 1123 - Which among the following theorems can be applied to any active or passive network?

Options:
1) Thevenin’s theorem
2) Tellegen theorem
3) Superposition theorem
4) Norton theorem
Correct Answer: Tellegen theorem
 
QID : 1124 - 

Options:
1) 2 A and 2 ohms
2) 3.5 A and 1 ohms
3) 0.41 A and 4.4 ohms
4) 1 A and 2 ohms
Correct Answer: 0.41 A and 4.4 ohms

QID : 1125 - An RLC resonant circuit has a resonance frequency of 2.5 mHz and a bandwidth of 20 kHz. If capacitance is 115 pF, then effective resistance (in ohms) of the circuit will be ___________.

Options:
1) 29.5
2) 4.7
3) 14.75
4) 2.66
Correct Answer: 2.66
 
QID : 1126 - The current at resonance in RLC series circuit is ______________.

Options:
1) Maximum
2) Minimum
3) Zero
4) Infinite
Correct Answer: Maximum
 
QID : 1127 - The SI unit of reactive power and apparent power are _______ and _______ respectively.

Options:
1) VAR and VA
2) kVA and VAR
3) VA and kV
4) kA and VA
Correct Answer: VAR and VA

QID : 1128 - A parallel RLC circuit has 25 ohm resistor, 10 mH inductor and a 2.5 µF capacitor connected in parallel across a 50 V, 100 Hz AC supply. Calculate the total impedance, conductance and admittance produced by the circuit.

Options:
1) 

2) 

3) 

4) 

Correct Answer: 
 
QID : 1129 - 

Options:
1) 1.1456 A

2) 0 A

3) 0.074 A

4) 1.234 A
Correct Answer: 0.074 A
 
QID : 1130 - 

Options:
1) 200

2) 400

3) 0

4) 1000
Correct Answer: 1000

 
QID : 1131 - What does the superposition theorem determines when applied to a linear network?

Options:
1) The current and voltage responds
2) Only current responds
3) Only voltage responds
4) The power responds
Correct Answer: The current and voltage responds
 
QID : 1132 - What is the condition for the maximum power delivered from a source to its load?

Options:
1) Load resistance greater than the source resistance
2) Load resistance less than the source resistance
3) Load resistance equal the source resistance
4) Load resistance less than or equal to the source resistance
Correct Answer: Load resistance equal the source resistance
 
QID : 1133 - A series RC circuit has 5 k-Ω resistor and a 2.5 µF capacitor connected across 20 V, 500 Hz supply. Calculate the total impedance and conductive reactance.

Options:
1) 

2) 

3) 

4) 

Correct Answer: 

QID : 1134 - The relation between the line voltage and the phase voltage in a delta connected load is given by:

Options:
1) Line voltage > phase voltage
2) Line voltage = phase voltage
3) Line voltage = √3 Phase voltage
4) Line voltage = 1/√3 Phase voltage
Correct Answer: Line voltage = phase voltage

QID : 1135 - In a balanced star connected power system the line voltage is 480 volts then calculate the phase voltage.

Options:
1) 277.1 V
2) 480 V
3) 470 V
4) 831.3 V
Correct Answer: 277.1 V
 
QID : 1136 - What is the term for the power factor in an RLC series circuit, just below and just above the resonant frequency respectively?

Options:
1) Both lagging
2) Both leading
3) Lagging and leading
4) Leading and lagging
Correct Answer: Leading and lagging
 
QID : 1137 - A star connected network consumes a power of 20 kW with a power factor of 0.8. Calculate the value of resistance of each coil when a supply voltage of 230 volts and 50 Hz is supplied between two phases of the network.

Options:
1) 8 ohms
2) 1.23 ohms
3) 1 ohm
4) 1.692 ohms
Correct Answer: 1.692 ohms
 
QID : 1138 - Calculate the impedance, if inductive reactance is 100 ohms and resistance is 150 ohms.

Options:
1) 150 ohms
2) 141.4 ohms
3) 180.27 ohms
4) 100 ohms
Correct Answer: 180.27 ohms

QID : 1139 - Which among the following has SI unit of siemens?

Options:
1) Conductance
2) Inductance
3) Resistance
4) Impedance
Correct Answer: Conductance

QID : 1140 - How much electricity is consumed by a 200-watt bulb, when kept ON for at least 8 hours continuously?

Options:
1) 100 watts
2) 1600 watts per hour
3) 100 watts per hour
4) 1 kilo watt hour
Correct Answer: 1600 watts per hour

QID : 1141 - Determine the resolution of a flash type ADC which employs 25 comparators with a reference voltage of 10 volts.

Options:
1) 0.625 V

2) 0.656 V

3) 0.3125 V

4) 0.525 V
Correct Answer: 0.3125 V
 
QID : 1142 - which gate has the highest speed of operation.

Options:
1) ECL gate
2) Universal gate
3) Logic gate
4) Both logic and universal gate
Correct Answer: ECL gate
 
QID : 1143 - A full adder combinational circuit has _______.

Options:
1) 3 inputs and 2 outputs
2) 2 inputs and 0 outputs
3) 1 input and 0 output
4) 4 inputs and 1 output
Correct Answer: 3 inputs and 2 outputs
 
QID : 1144 - The memory that uses one transistor and one capacitor as a basic memory unit is _______.

Options:
1) DRAM
2) SRAM
3) RAM
4) Both SRAM and DRAM
Correct Answer: DRAM
 
QID : 1145 - Which among the following multivibrators is unstable in any state?

Options:
1) Astable multivibrator
2) Bistable multivibrator
3) Monostable multivibrator
4) Both astable and bistable multivibrator
Correct Answer: Astable multivibrator
 
QID : 1146 - 

  
Options:
1) NOR gate
2) XNOR gate
3) AND gate
4) OR gate
Correct Answer: NOR gate
 
QID : 1147 - A 4 bit uniform quantization PCM system can attain a signal ranging from -2 to +2 V. The rms value of the signal is 0.5 V. What is the signal to quantization noise ratio?

Options:
1) 30 dB
2) 46.91 dB
3) 25.84 dB
4) 40 dB
Correct Answer: 25.84 dB

QID : 1148 - Quantization is a _______ and a/an _______ process.

Options:
1) Non-linear and irreversible
2) Linear and irreversible
3) Non-linear and reversible
4) Linear and reversible
Correct Answer: Non-linear and irreversible
 
QID : 1149 - If the current flowing in the antenna is 17 A which radiates a signal of power 15.028 kW, then what will be the radiation resistance (in ohms) of the antenna?

Options:
1) 3.2

2) 5.2

3) 32

4) 52
Correct Answer: 52
 
QID : 1150 - The antenna current of an AM transmitter is 6 A. Determine the antenna current of the transmitter when the percent of modulation changes to 0.4.

Options:
1) 9.19 A

2) 7.56 A

3) 6.23 A

4) 9.91 A
Correct Answer: 6.23 A
 
QID : 1151 - Calculate the speed capacity of the channel (in Mbps) when the TV picture is transmitted over a channel of with 25 dB S/N ratio.

Options:
1) 72 Mbps
2) 27 Mbps
3) 92 Mbps
4) 74.4 Mbps
74.4 एमबीपीएस
Correct Answer: 74.4 Mbps

QID : 1152 - In delta modulation system, the granular noise is produced by which of the following?

Options:
1) Pulse rate decrease
2) Pulse amplitude decreases
3) Modulating signals increase
4) Modulating Signals remains constant
Correct Answer: Modulating Signals remains constant
 
QID : 1153 - Which among the following transmits the data samples over a single channel?

Options:
1) TDM
2) FDM
3) PCM
4) PTM
Correct Answer: TDM

QID : 1154 - Which signal is generated by using a mono stable multivibrator?

Options:
1) PCM
2) TDM
3) PAM
4) PWM
Correct Answer: PCM

QID : 1155 - Which filter is used to detect the PAM signal?

Options:
1) Low pass filter
2) High pass filter
3) Band pass filter
4) All band pass filter
Correct Answer: Low pass filter
 
QID : 1156 - Find the 2’s compliment of a 8 bit number that is represented as 28 in decimal number system.

Options:
1) 11010110

2) 11100100

3) 00011101

4) 11100010
Correct Answer: 11100100
 
QID : 1157 - Pilot carrier in SSB modulation is used for

Options:
1) To provide better noise immunity
2) Low power consumption
3) Frequency stability
4) Reduction of carrier frequency
Correct Answer:  Frequency stability

QID : 1158 - FSK modulation is mostly applied in

Options:
1) Telegraphy
2) Fiber transmission line
3) Waveguide
4) Tuned circuit
Correct Answer: Telegraphy

QID : 1159 - Pre- emphasis circuit in FM transmitter is used

Options:
1) to increase the bandwidth of the side band.
2) to improve the signal to noise ratio at low audio frequencies.
3) to improve the signal to noise ratio at high audio frequencies.
4) to increase the carrier power.
Correct Answer: to improve the signal to noise ratio at high audio frequencies.

QID : 1160 - Arrange the following components sequentially from the output to input in a super heterodyne receiver.

i. Antenna
ii. IF amplifier
iii. Mixer
iv. Audio amplifier

Options:
1) i, ii, iii and iv
2) iv, iii, ii and i
3) i, iii, iv and ii
4) iv, ii, iii, and i
Correct Answer: iv, ii, iii, and i
 
QID : 1161 - The auto correction function of white noise is represented as ____________.

Options:
1) uniform
2) delta
3) gaussian
4) non-uniform
Correct Answer: delta

QID : 1162 - Optical fiber operates in

Options:
1) Visible light band
2) Ultraviolet band
3) Infra red band
4) Ultraviolet, visible and infrared band
Correct Answer: Ultraviolet, visible and infrared band

QID : 1163 - The output of source encoder is

Options:
1) An analog signal
2) Sequence of binary digits
3) A digital signal
4) A triangular wave
Correct Answer: Sequence of binary digits
 
QID : 1164 - In a parallel RL circuit, the current always _____ the applied voltage.

Options:
1) leads
2) lags
3) remains in phase with
4) None of these
Correct Answer: lags
 
QID : 1165 - Which modulator is used for the generation of DSB-SC signal?

Options:
1) Balanced modulator
2) Square law modulator
3) Armstrong phase modulator
4) Envelope detector
Correct Answer: Balanced modulator

QID : 1166 - What is the frequency range of VHF in electromagnetic spectrum?

Options:
1) 30 MHz to 300 MHz

2) 3 GHz to 30 GHz

3) 30 GHz to 300 GHz

4) 3 MHz to 30 MHz
Correct Answer: 30 MHz to 300 MHz
 
QID : 1167 - Waveguides are employed as a transmission lines for propagation of

Options:
1) Analog signals
2) Digital signals
3) Line signals
4) Microwave signals
Correct Answer: Microwave signals
 
QID : 1168 - What is the frequency range of UHF signals?

Options:
1) 3 MHz to 30 MHz

2) 25 MHz to 3 GHz

3) 300 MHz to 3 GHz

4) 300 kHz to 3 MHz
Correct Answer: 300 MHz to 3 GHz
 
QID : 1169 - What is the function of transmitter in the communication system?

Options:
1) Provides the information
2) Processes the information
3) Modulates the signal
4) Rectify the input signal
Correct Answer: Processes the information
 
QID : 1170 - Noise is measured in_______.

Options:
1) Decibel
2) Mel
3) Phon
4) Zone
Correct Answer: Decibel
 
QID : 1171 - Correlation receiver and phase locked loop are used in____________.

Options:
1) FSK reception.
2) PSK reception.
3) ASK reception.
4) both ASK and PSK.
Correct Answer: FSK reception.
 
QID : 1172 - Which of the following modulating techniques requires minimum bandwidth?

Options:
1) Delta modulation
2) PCM
3) PAM
4) DPCM
Correct Answer: Delta modulation
 
QID : 1173 - Which of the following is not used for the demodulation of SSB?

Options:
1) Product demodulator
2) Diode balanced modulator
3) Complete phase shift generator
4) Bipolar transistor balanced modulator
Correct Answer: Bipolar transistor balanced modulator
 
QID : 1174 - Which of the following block is not present in AM but present in FM receivers?

Options:
1) RF amplifier
2) Slope detector
3) IF amplifier
4) Mixer
Correct Answer: Slope detector
 
QID : 1175 - Attenuation per unit length in a coaxial cable with frequency‌‌‌‌‌‌_____.

Options:
1) Increases
2) Decreases
3) Remains constant
4) Becomes Zero
Correct Answer: Increases

QID : 1176 - Nyquist interval rate for the signal x(t) = cos c (2000 t) + cos c (500 t), is_______.

Options:
1) 700 Hz
2) 1400 Hz
3) 4 kHz
4) 5 kHz
Correct Answer: 4 kHz

QID : 1177 - Which of these are the digital modulation techniques?

Options:
1) ASK
2) PAM
3) FM
4) PCM
Correct Answer: PCM

QID : 1178 - Which of the following is NOT correct when referring to AM and FM?

Options:
1) FM is more susceptible to noise as compared to AM
2) AM can transmit at longer distance as compared to FM.
3) Phase remains constant in AM.
4) FM signal has higher bandwidth than AM
Correct Answer: AM can transmit at longer distance as compared to FM.
 
QID : 1179 - Which local oscillator is used in radio receiver?

Options:
1) Crystal oscillator
2) Hartley oscillator
3) RC-phase shift oscillator
4) Wein-bridge oscillator
Correct Answer: Hartley oscillator
 
QID : 1180 - Audio and video signal in the television broadcast is done by_________.

Options:
1) Amplitude and Frequency modulation
2) Phase and amplitude modulation
3) Frequency and angle modulation
4) Both by frequency modulation
Correct Answer: Amplitude and Frequency modulation
 
QID : 1181 - Which among the following is/are the advantages of digital communication?

Options:
1) Simple multiplexing
2) Reliable
3) Easy processing and signaling
4) All of the these
Correct Answer: All of the these
 
QID : 1182 - Which among the given expressions is the Product of Sum form?

Options:
1) (b+c)(a+b)

2) ac-bd

3) ab+cd

4) ab(cd)
Correct Answer: (b+c)(a+b)
 
QID : 1183 - The distributive law of Boolean algebra states:

Options:
1) 

2) 

3) 

4) 

Correct Answer: 

QID : 1184 - The Boolean expression AB + ABC equals.

Options:
1) BC

2) ABC

3) AB + BC

4) AB
Correct Answer: AB
 
QID : 1185 - 

Options:
1) 

2) 

3) 

4) 

Correct Answer: 

 
QID : 1186 - Calculate the baud rate of the ASK signal having the bit rate of 300 bps.

Options:
1) 100
2) 250
3) 300
4) 75
Correct Answer: 300
 
QID : 1187 - Which among the following are the advantages of Yagi antenna?
i. It has gain to allow lower strength
ii. The antenna becomes strong for high gain levels
iii. It can be easily mounted
iv. It is mechanically relatively straight forward.

Options:
1) i, iii and iv
2) i, ii and iv
3) ii, iii, and iv
4) Only ii
Correct Answer: i, iii and iv

QID : 1188 - The propagation of radio wave signals through reflection from ionosphere is known as________.

Options:
1) Sky wave propagation
2) Ground wave propagation
3) Space wave propagation
4) Tropospheric wave propagation
Correct Answer: Sky wave propagation

QID : 1189 - Which array uses two half wave dipoles spaced along with one-half wavelength apart?

Options:
1) Broad-end array
2) End-fire array
3) Back-fire array
4) Binomial array
Correct Answer: End-fire array

QID : 1190 - Broadside antenna array is ________ in nature and has ____ gain.

Options:
1) Unidirectional and low
2) Multidirectional and very low
3) Bidirectional and high
4) Both unidirectional and multidirectional 
Correct Answer: Bidirectional and high

QID : 1191 - What is the maximum distance up to which the TV transmission can be received if the height of a TV broadcasting tower is 85 meter ? (Radius of earth = 6,400,000 m)

Options:
1) 62 km
2) 31 km
3) 32.98 km
4) 30 km
Correct Answer: 32.98 km
 
QID : 1192 - Calculate the radiation resistance of an antenna of length λ/8 m ( λ is the wavelength).

Options:
1) 10
2) 8
3) 12.33
4) 12.8
Correct Answer: 12.33
 
QID : 1193 - In which of the following the phase of the carrier wave changes in accordance with intensity of light.

Options:
1) AM
2) PM
3) FM
4) PAM
Correct Answer: PM
 
QID : 1194 - VSB modulation is termed as ___________.

Options:
1) Vestigial side band
2) Vertical side band
3) Single side-band
4) Variable side band
Correct Answer: Vestigial side band

QID : 1195 - Which of the following is/are the advantages of DSB-SC over SSB-SC?

I. It has lower power consumption
II. It needs half of the bandwidth
III. It is used for transmitting stereo information
IV. It has two side bands with no carrier

Options:
1) I only
2) I,II and IV
3) I,III and IV
4) II only
Correct Answer: I,III and IV
 
QID : 1196 - What is the main advantage of parabolic antenna?

Options:
1) High directivity
2) wide bandwidth
3) small wavelength
4) low directivity
Correct Answer: High directivity
 
QID : 1197 - For an amplitude modulated wave, he maximum amplitude is found to be 20 V while the minimum amplitude to be 4.5 V. Calculate the modulation index.

Options:
1) 0.62

2) 0.67

3) 0.26

4) 0.632
Correct Answer: 0.632
 
QID : 1198 - Modulation index is generally kept________.

Options:
1) Less than 1
2) Greater than 1
3) Equal to 1
4) Zero
Correct Answer: Less than 1
 
QID : 1199 - Which of the following modulations has higher bandwidth among the others?  

Options:
1) PCM
2) DM
3) ADM
4) DPCM
Correct Answer: PCM
 
QID : 1200 - Encoding technique is selected on the basis of

i. Efficiency
ii. Error
iii. Power level

Options:
1) Only i
2) Only ii
3) Only iii
4) i, ii and iii
Correct Answer: i, ii and iii
 

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