SSC Scientific Assistant (IMD) Exam : Held on 24-Nov-2017 Shift-2 (Electronics)
SSC Scientific Assistant (IMD) Exam : Held on 24-Nov-2017 Shift-2
(Electronics)
QID : 1101 - Which of the following materials offers highest resistivity?
Options:
1) Tungsten
2) Germanium
3) Silicon
4) Ceramic
Correct Answer: Ceramic
QID : 1102 - Which of the following shows a form of energy stored in an insulator?
Options:
1) Electric charge
2) Mechanical energy
3) Magnetic field
4) Electrostatic field
Correct Answer: Magnetic field
QID : 1103 - Which of the following shows a form of energy stored in a capacitor?
Options:
1) Current Flow
2) Mechanical Energy
3) Magnetic Field
4) Electrostatic Field
Correct Answer: Electrostatic Field
QID : 1104 - Select the colour code for a carbon resistor with a value of 64,000 ± 1% Ohms.
Options:
1) Blue-yellow-orange-brown
2) Red-brown-blue-yellow
3) Green-yellow-orange-red
4) Yellow-green-red-brown
Correct Answer: Blue-yellow-orange-brown
QID : 1105 -
Options:
1) 22.5
2) 27.5
3) 32.5
4) 37.5
Correct Answer: 37.5
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QID : 1106 - Which of the following component gives smooth DC output?
Options:
1) Clamper
2) Regulator
3) Clipper
4) Rectifier
Correct Answer: Regulator
QID : 1107 - Which of the following is a bilateral electric device?
Options:
1) Resistor
2) Diode
3) LED
4) BJT
Correct Answer: Resistor
QID : 1108 - What is the output of a half wave rectifier (in V) when it is supplied with a voltage which has peak value of 12.5 V?
Options:
1) 2
2) 4
3) 6
4) 8
Correct Answer: 4
QID : 1109 - Which of the following diodes is also known as hot carrier diode?
Options:
1) PN Diode
2) LED
3) Schottky Diode
4) Varactor Diode
Correct Answer: Schottky Diode
QID : 1110 -
Options:
1) PN Diode
2) LED
3) Schottky Diode
4) Varactor Diode
Correct Answer: Schottky Diode
QID : 1111 - Which of the following quantities is boosted by this circuit when a BJT is connected in a circuit in common base configuration?
Options:
1) Power
2) Input Resistance
3) Output Resistance
4) current gain
Correct Answer: Power
QID : 1112 - Which of the following can be used in the fabrication of p-type semiconductor?
Options:
1) Aluminium
2) Arsenic
3) Antimony
4) Bismuth
Correct Answer: Aluminium
QID : 1113 - Which of the following are the functions of a transistor?
Options:
1) Switching device and fixed resistor
2) Tuning device and rectifier
3) Variable resistor and switching device
4) Rectifier and fixed resistor
Correct Answer: Variable resistor and switching device
QID : 1114 - Which of the following voltages has the highest positive value in PNP transistor circuit?
Options:
1) Ground
2) Vc
3) VBE
4) V0
Correct Answer: Ground
QID : 1115 - What is the minimum number of CMOS required for constructing a two input NOR logic gate?
Options:
1) 1
2) 2
3) 3
4) 4
Correct Answer: 4
QID : 1116 - Which of the following is NOT a type of classes of power amplifier?
Options:
1) A
2) C
3) D
4) M
Correct Answer: M
QID : 1117 - What is the value of voltage gain in emitter follower transistor configuration?
Options:
1) 0
2) 0.318
3) 1
4) 1.5
Correct Answer: 1
QID : 1118 - What is the typical range of output frequency of a relaxation oscillator?
Options:
1) 20 Hz to 20 kHz
2) 0 Hz to 200 Hz
3) 0 Hz to 20 MHz
4) 20 Hz to 20 GHz
Correct Answer: 0 Hz to 20 MHz
QID : 1119 - Which of the following factor does NOT affect the stability of an oscillator?
Options:
1) Circuit components
2) Phase
3) Input voltage
4) Stray capacitance
Correct Answer: Phase
QID : 1120 - What is the ratio of change in output current and change in input voltage in a JFET is known as?
Options:
1) Admittance
2) Gain
3) Resistivity
4) Transconductance
Correct Answer: Transconductance
QID : 1121 - Which of the following has the equal root mean square voltage and peak voltage?
Options:
1) Saw tooth wave
2) Sinusoidal wave
3) Square wave
4) Triangular wave
Correct Answer: Square wave
QID : 1122 - If a resistive load is supplied by a source in which the voltage and the current both have frequency of 110 Hz, the frequency of instantaneous power is _______.
Options:
1) 50 Hz
2) 55 Hz
3) 110 Hz
4) 220 Hz
Correct Answer: 220 Hz
QID : 1123 -
Options:
1) 2 A
2) 2.5 A
3) 3 A
4) 3.5 A
Correct Answer: 2.5 A
QID : 1124 - The Norton theorem reduces a circuit to which of the following circuits?
Options:
1) A current source only
2) A current source with an impedance in parallel
3) A current source with an impedance in series
4) A voltage source only
Correct Answer: A current source with an impedance in parallel
QID : 1125 -
Options:
1) 1.5
2) 3
3) 4.5
4) 6
Correct Answer: 6
QID : 1126 - What is the amount of charge stored (in C) in a capacitor having capacitance of 0.008 F and a voltage of 16 V applied across it?
Options:
1) 0.0005
2) 0.008
3) 0.64
4) 0.128
Correct Answer: 0.128
QID : 1127 - What is the approximate value of capacitance (in Farad) of earth if (radius = 6,400 km)?
Options:
1) 0.0000007
2) 0.000007
3) 0.00007
4) 0.0007
Correct Answer: 0.0007
QID : 1128 - What is the power dissipation (in W) in an ideal inductor having an inductance of 0.2 H?
Options:
1) -0.04
2) -0.2
3) 0
4) 0.04
Correct Answer: 0
QID : 1129 - Calculate the peak value of the source voltage (in V) if the root-mean square voltage across the resistor and inductor in a series RL circuit is 13 V and 12 V, respectively.
Options:
1) 1
2) 17.68
3) 25
4) 35.35
Correct Answer: 35.35
QID : 1130 - Calculate the admittance (in Siemens) of a series RC circuit having resistance of 15 Ohms and capacitance of 0.1 mF which is supplied by a source having frequency of 50 Hz.
Options:
1) 0.03
2) 0.3
3) 3
4) 30
Correct Answer: 0.3
QID : 1131 - Calculate the power factor of a series RL circuit having the conductance of 30 Siemens and the susceptance of 40 Siemens.
Options:
1) 0.2
2) 0.4
3) 0.6
4) 0.8
Correct Answer: 0.6
QID : 1132 - Which of the following is TRUE in case of the admittance of a circuit?
Options:
1) It is the measure of flow of current which is allowed by the circuit.
2) It is the measure of voltage supplied to the circuit.
3) It is the measure of the resistance offered by the circuit.
4) It is the measure of the power dissipated in the circuit.
Correct Answer: It is the measure of flow of current which is allowed by the circuit.
QID : 1133 -
Options:
1) 1
2) 2
3) 3
4) 4
Correct Answer: 2
QID : 1134 - What is the quality factor of a series RLC circuit having resistance, capacitance and inductance of 10 ohms, 90 mH and 0.1 mF, respectively?
Options:
1) 0.3
2) 0.9
3) 3
4) 9
Correct Answer: 3
QID : 1135 - Calculate the resonant frequency (in radians/sec) of a series RLC circuit having resistance of 15 Ohms, inductance of 25 mH and capacitance of 0.25 mF.
Options:
1) 0.4
2) 4
3) 40
4) 400
Correct Answer: 400
QID : 1136 - Calculate the bandwidth (in Hz) of a series RLC circuit having resistance of 50 Ohms and inductance of 25 mH.
Options:
1) 159.155
2) 318.31
3) 636.62
4) 1273.24
Correct Answer: 318.31
QID : 1137 - A star connected network consumes 1.8 kW at 0.5 lagging power factor when connected to a 230 V, 50 Hz source. Calculate the per phase impedance (in Ohms) of the star network.
Options:
1) 2.8
2) 3.6
3) 7.4
4) 14.7
Correct Answer: 14.7
QID : 1138 - A delta connected load has phase current of 5 A and has equal phase impedance of (12 + j 5) Ohms. Calculate the value of line voltage (in Volts) supplying a delta connected load.
Options:
1) 112.58
2) 200
3) 220
4) 225.16
Correct Answer: 112.58
QID : 1139 - If a star network has three equal resistances of 80 Ohms, calculate the equivalent delta network resistance (in Ohms) in each phase.
Options:
1) 26.67
2) 80
3) 160
4) 240
Correct Answer: 240
QID : 1140 - Which of the following values must be same for a balanced three phase circuit?
I. Impedance
II. Resistance
III. Reactance
IV. Power factor
Options:
1) Only (I)
2) Only (II)
3) Only (III) and (IV)
4) (I), (II), (III) and (IV)
Correct Answer: (I), (II), (III) and (IV)
QID : 1141 - Which of the following Boolean expression expresses the logic condition ‘If A = 1 and B = 0 or A = 0 and B = 1, only then the output Y = 0’?
Options:
1)
2)
3)
4)
Correct Answer:
QID : 1142 -
Options:
1) AND
2) NAND
3) NOR
4) XNOR
Correct Answer: XNOR
QID : 1143 - What is the number of possibilities of low output from a 3-input OR gate?
Options:
1) 1
2) 2
3) 4
4) 7
Correct Answer: 1
QID : 1144 - What is the number of possibilities of low output from a 3 - input AND gate?
Options:
1) 1
2) 2
3) 4
4) 7
Correct Answer: 7
QID : 1145 -
Options:
1) AND
2) OR
3) XOR
4) XNOR
Correct Answer: XOR
QID : 1146 - The group of bits 01100 is serially shifted (right-most bit first) into a 5 bits parallel output shift register with an initial state of 01011. What is the value contained in the register after 2 clock pulses?
Options:
1) {00001}
2) {00010}
3) {10001}
4) {10011}
Correct Answer: {00010}
QID : 1147 - What is the number of flip-flops required to produce a divide-by 32 device?
Options:
1) 4
2) 5
3) 6
4) 7
Correct Answer: 5
QID : 1148 -
Options:
1)
2)
3)
4)
Correct Answer:
QID : 1149 - What is the resolution of a 0-5 V 16-bit DAC?
Options:
1) 0.0019
2) 0.0039
3) 0.0078
4) 0.0156
Correct Answer: 0.0019
QID : 1150 - Convert the binary number 10101110 to octal.
Options:
1) 128
2) 184
3) 256
4) 312
Correct Answer: 256
QID : 1151 - Which of the following device gives the electromagnetic wave as output when fed by a high frequency electric current?
Options:
1) Amplifier
2) Antenna
3) Loudspeaker
4) Microphone
Correct Answer: Antenna
QID : 1152 - What is the horizontal pointing angle of an antenna called?
Options:
1) Azimuth
2) Angle of elevation
3) Angle of depreciation
4) Beam width
Correct Answer: Azimuth
QID : 1153 - Which of the following methods can be used to increase the antenna gain?
Options:
1) Addition of several antennas in parallel
2) Addition of several antennas in series
3) Increasing the thickness of antenna rods
4) Focusing radiated energy in one desired direction
Correct Answer: Focusing radiated energy in one desired direction
QID : 1154 - A dipole antenna has a radiation resistance of 3 Ohms and carries a current of 40 A. What is the value of power radiated by the antenna (in kW)?
Options:
1) 2.3
2) 3.8
3) 4.8
4) 5.3
Correct Answer: 4.8
QID : 1155 - Which of the following is TRUE about an ungrounded antenna near the ground?
Options:
1) It acts as a single antenna of twice the height.
2) It acts as a single antenna of half the height.
3) It needs to be placed horizontally to perform actively.
4) It acts as an antenna array.
Correct Answer: It acts as an antenna array.
QID : 1156 - Choose the frequency which lies in the low frequency range.
Options:
1) 50 Hz
2) 5 kHz
3) 50 kHz
4) 5 MHz
Correct Answer: 50 kHz
QID : 1157 - What is the average range (in km) for radio wave propagation through VHF communications?
Options:
1) 25
2) 50
3) 150
4) 200
Correct Answer: 50
QID : 1158 - Calculate the refractive index of a medium if it allows light to travel 200 metres in same time in which the light travels 320 metres in air?
Options:
1) 0.625
2) 1
3) 1.6
4) 1.85
Correct Answer: 1.6
QID : 1159 - Which of the following reasons is true for a radio path horizon to exceed the geometric path horizon in radio wave propagation?
Options:
1) The radio wave skips the E-layer
2) The radio wave skips the D-layer
3) The radio wave skips the auroral
4) The radio wave can be bent
Correct Answer: The radio wave can be bent
QID : 1160 - What is the maximum reusable frequency (in kHz) of an HF signal, if its critical frequency has a value of 4064.64 kHz at 60 degree incidence?
Options:
1) 2032.32
2) 2874.13
3) 5748.27
4) 8129.28
Correct Answer: 8129.28
QID : 1161 - Which among the following separates the oscillator from the load in a radio transmitter?
Options:
1) Buffer
2) Comparator
3) Mixer
4) Oscillator
Correct Answer: Buffer
QID : 1162 - What will be the modulation index of a modulated wave if the modulated peak value of a signal is 130 V and the unmodulated carrier peak value is 65 V?
Options:
1) 0.13
2) 0.5
3) 1
4) 2
Correct Answer: 2
QID : 1163 - Which of the following is the advantage of phase modulation over direct frequency modulation?
Options:
1) Multipliers can be used
2) Small deviation is obtained
3) Easy practical application
4) Oscillator can be controlled by crystal
Correct Answer: Oscillator can be controlled by crystal
QID : 1164 - What will be the change in transmitted power (in Watt) if the antenna current which was 800 mA at 50 W is reduced to 500 mA?
Options:
1) 12.5
2) 19.53
3) 30.47
4) 37.5
Correct Answer: 30.47
QID : 1165 - An AM broadcast station is found to be transmitting modulating frequencies up to 5 kHz and the station is allowed to transmit on a frequency of 950 kHz, then what will be the bandwidth (in kHz) allotted to the station?
Options:
1) 5
2) 10
3) 20
4) 25
Correct Answer: 10
QID : 1166 - What will be the power transmitted (in Watt) by the AM transmitter if the carrier wave power is 150 W and the carrier wave is 60% modulated?
Options:
1) 1.5
2) 13.5
3) 16.5
4) 25.5
Correct Answer: 13.5
QID : 1167 - What is the percentage of power saved when an 80% modulated wave is transmitted over SSB-SC which was initially transmitted over AM?
Options:
1) 0.8568
2) 0.8666
3) 0.8788
4) 0.8988
Correct Answer: 0.8788
QID : 1168 - What is the power transmitted (in W) by a DSB-SC signal when the carrier wave power is 80 W and modulation index is 0.4?
Options:
1) 6.4
2) 9.8
3) 12.6
4) 16.2
Correct Answer: 6.4
QID : 1169 - Calculate the antenna current (in A) having impedance of 20 Ohms if a 60% amplitude modulated wave is transmitted with the help of a 50 W carrier wave.
Options:
1) 1.03
2) 1.28
3) 1.69
4) 1.72
Correct Answer: 1.72
QID : 1170 - Which of the following part of a carrier wave is affected during the modulation in AM?
Options:
1) Amplitude
2) Frequency
3) Phase
4) Angle
Correct Answer: Amplitude
QID : 1171 - Which of the followings are associated with AM?
I. DSB-FC
II. DSB-SC
III. SSB-SC
IV. VSB
Options:
1) I only
2) II only
3) II and IV only
4) I, II, III and IV
Correct Answer: I, II, III and IV
QID : 1172 - Which among the following uses de-emphasis circuit?
Options:
1) FM receiver
2) FM transmitter
3) VSB receiver
4) VSB transmitter
Correct Answer: FM receiver
QID : 1173 - Which of the following constitutes emphasis system in FM?
I. Pre-emphasis
II. Intermediate-emphasis
III. De-emphasis
IV. Post-emphasis
Options:
1) I only
2) I and IV only
3) I and III only
4) II and III only
Correct Answer: I and III only
QID : 1174 - Which of the following is TRUE about the power of a FM signal if the modulation index becomes halved?
Options:
1) Power becomes four times the previous value
2) Power becomes two times the previous value
3) Power remains same
4) Power becomes half of the previous value
Correct Answer: Power remains same
QID : 1175 - Which of the following contains a limiter stage, a discriminator and a de-emphasis circuit?
Options:
1) Direct FM transmitter
2) Indirect FM transmitter
3) Double Side Band AM receiver
4) FM receiver
Correct Answer: FM receiver
QID : 1176 - Calculate the carrier swing (in kHz) of the FM signal if a 90 MHz carrier is frequency modulated by 10 kHz and having a frequency deviation of 60 kHz.
Options:
1) 60
2) 90
3) 100
4) 120
Correct Answer: 120
QID : 1177 - Choose the areas where the pulse modulation is used?
I. Radio Navigation
II. Automatic Flight Landing Equipment
III. Data Communications
Options:
1) I only
2) II only
3) III only
4) I, II and III
Correct Answer: I, II and III
QID : 1178 - Which of the following is associated with pulse modulation?
Options:
1) Gamma waves
2) LF band
3) Microwave
4) Telegraphy
Correct Answer: Microwave
QID : 1179 - Which of the following is the advantage of AM over FM?
Options:
1) High Quality
2) Large coverage area
3) Low interference
4) Noise reduction
Correct Answer: Large coverage area
QID : 1180 - Which of the followings are the reasons for use of narrow-band FM rather than wide-band FM?
I. It improves signal to noise ratio.
II. It reduces inter-channel interference.
III. Efficient use of power for better coverage.
Options:
1) I, II and III
2) II and III only
3) I and II only
4) III only
Correct Answer: I, II and III
QID : 1181 - What are the new frequencies outside the regular spectrum called?
Options:
1) Distortion
2) Harmonics
3) Interference
4) Splatter
Correct Answer: Splatter
QID : 1182 - What is the correct sequence of the blocks in an AM receiver from receiving the signal to output?
Options:
1) RF amplifier - Mixer - IF amplifier - Demodulator - Audio amplifier
2) RF amplifier - Mixer - IF amplifier - Audio amplifier - Demodulator
3) IF amplifier - Demodulator - RF amplifier - Mixer - Audio Amplifier
4) Audio Amplifier - Mixer - Demodulator - IF amplifier - RF amplifier
Correct Answer: RF amplifier - Mixer - IF amplifier - Demodulator - Audio amplifier
QID : 1183 - What is the Nyquist time interval (in ms) between two successive samples while sampling a signal having maximum frequency of 5 kHz?
Options:
1) 0.01
2) 0.1
3) 1
4) 10
Correct Answer: 0.1
QID : 1184 - Which of the following is TRUE when the sampling time becomes less than the Nyquist interval?
Options:
1) Original signal can be recreated
2) Bandwidth decreases
3) Bandwidth increases
4) Channel capacity decreases
Correct Answer: Original signal can be recreated
QID : 1185 - Which of the followings are digital modulation techniques?
I. SSB-SC
II. PCM
III. Delta Modulation
IV. VSB
Options:
1) II and IV only
2) III and IV only
3) I and IV only
4) I and II only
Correct Answer: I and II only
QID : 1186 - What is the use of Schmitt trigger in PWM signal reception?
Options:
1) For better synchronization
2) To produce ramp signal
3) To remove noise
4) For better selectivity
Correct Answer: To remove noise
QID : 1188 - Choose the areas where the multiplexing is used?
I. Packet switching
II. Circuit switching
III. Data switching
Options:
1) I only
2) II only
3) III only
4) I and II only
Correct Answer: II only
QID : 1189 - Calculate the transmission rate (in kbps) of TDM if the link transmits 2,000 frames per second and each slot has 16 bits.
Options:
1) 8
2) 16
3) 32
4) 64
Correct Answer: 32
QID : 1190 - Which of the following is a disadvantage of FDM?
Options:
1) Complexity in demodulation
2) Only one signal can be transmitted at a given time
3) Need of synchronization between transmitter and receiver
4) Cross talk occurs
Correct Answer: Cross talk occurs
QID : 1191 - What is the relation between the bandwidth of ASK modulated signal and baseband signal?
Options:
1) Modulated signal bandwidth is one-fourth of the bandwidth of baseband signal.
2) Modulated signal bandwidth is half of the bandwidth of baseband signal.
3) Modulated signal bandwidth is equal to the bandwidth of baseband signal.
4) Modulated signal bandwidth is double of the bandwidth of baseband signal.
Correct Answer: Modulated signal bandwidth is equal to the bandwidth of baseband signal.
QID : 1192 - Which of the following pair shares same probability of error?
Options:
1) ASK and FSK
2) ASK and PSK
3) FSK and PSK
4) ASK and QPSK
Correct Answer: FSK and PSK
QID : 1193 - Which among the following is NOT a common usage area of fibre-optic cable?
Options:
1) Computer Network
2) Consumer TV
3) Closed circuit TV
4) Long distance telephone systems
Correct Answer: Consumer TV
QID : 1194 - Which of the following is the principle of operation of fibre-optic cable?
Options:
1) Absorption
2) Dispersion
3) Distortion
4) Reflection
Correct Answer: Reflection
QID : 1195 - Which material is preferred for making the core of a fibre-optic cable?
Options:
1) Air
2) Diamond
3) Glass
4) Quartz
Correct Answer: Glass
QID : 1196 - What is the refractive index of the incident medium in a fibre-optic cable when the reflective index of reflective medium is 1.2 and critical angle is 30 degree?
Options:
1) 0.6
2) 1
3) 1.5
4) 2.4
Correct Answer: 2.4
QID : 1197 - Which modulation technique is mostly used in communication through satellites?
Options:
1) AM
2) FM
3) PAM
4) PCM
Correct Answer: FM
QID : 1198 - What is the minimum number of satellites needed for global communication?
Options:
1) 3
2) 6
3) 7
4) 8
Correct Answer: 3
QID : 1199 - Which of the following is best suited for satellite operation?
Options:
1) LF
2) HF
3) SHF
4) VHF
Correct Answer: VHF
QID : 1200 - Wavelength of 0.5 m lies in which of the following frequency range?
Options:
1) UHF
2) VHF
3) LF
4) SHF
Correct Answer: UHF
