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SSC Scientific Assistant (IMD) Exam : Held on 23 Nov 2017 Shift-1 (ELECTRONICS)

SSC Scientific Assistant (IMD) Exam : Held on 23 Nov 2017 Shift-1

(ELECTRONICS)

QID : 501 - Which of the following carriers cause current in a semiconductor?

1) Holes
2) Electrons
3) Protons and Holes
4) Electrons and holes

Correct Answer: Electrons and holes

QID : 502 - The SI unit of conductivity is _________.

1) Meter
2) Ohm-meter
3) Ohm
4) 1/(Ohm-meter)

Correct Answer: 1/(Ohm-meter)

QID : 503 - RGB LED consists of ___________ LED.

1) Two red, one green and one blue
2) One red, two green and one brown
3) One red, one green and one blue
4) two red, two green and two blue

Correct Answer: One red, one green and one blue

QID : 504 - Which capacitor is used as a high accuracy capacitor?

1) Ceramic capacitor
2) Mica capacitor
3) Variable capacitor
4) Tantalum capacitor

Correct Answer: Mica capacitor

QID : 505 - Potentiometer is a _____________.

1) Capacitor
2) Inductor
3) Resistor
4) Connector

Correct Answer: Resistor

QID : 506 - A diode consists of ________ junction/s.

1) Zero
2) One
3) Two
4) Three

Correct Answer: On

QID : 507 - What is the nature of current in a diode?

1. Unipolar
2. Bipolar

1) Only 1
2) Only 2
3) Both 1 and 2
4) Neither 1 nor 2

Correct Answer: Only 2

QID : 508 - Which of the following starts a free-running multivibrator?

1) An output signal
2) An input signal
3) An external circuit
4) None of the these

Correct Answer: None of the these

QID : 509 - A varistor is a ________.

1) a current dependent resistor
2) a voltage dependent resistor
3) a current dependent diode
4) a voltage dependent diode

Correct Answer: a voltage dependent resistor

QID : 510 - An Op-Amp has ___________inputs.

1) 1
2) 2
3) 3
4) 4

Correct Answer: 2

QID : 511 - _________ is used in operational amplifier to obtain desired output waveform.

1) Clipper
2) Schmitt trigger
3) Clamper
4) Sample and hold circuit

Correct Answer: Clipper

QID : 512 -

1) 5 A
2) 4.5 mA
3) 50 mA
4) 6 A

Correct Answer: 4.5 mA

QID : 513 - Which of the following statement is correct for JFET?

1) 2-terminal device
2) 3-terminal device
3) 4-terminal device
4) 5-terminal device

Correct Answer: 3-terminal device

QID : 514 -

1) Omega
2) Alpha
3) Beta
4) Pi

Correct Answer: Alpha

QID : 515 - Which of the following is the simplest type of a field-effect transistor?

1) MOSFET
2) JFET
3) IGBT
4) MESFET

Correct Answer: JFET

QID : 516 - Junction field-effect transistor (JFET) has __________diodes.\

1) 1
2) 2
3) 3
4) 4

Correct Answer: 2

QID : 517 - Enhancement mode is present in ________.

1) tunnel diode
2) PIN diode
3) JFET
4) MOSFET

Correct Answer: MOSFET

QID : 518 -

1) 20.57
2) 24.57
3) 25.87
4) 28.57

Correct Answer: 25.87

QID : 519 - Transistor operates as a closed switch in ______________ region.

1) saturation region
2) cutoff region
3) active region
4) both saturation and cutoff region

Correct Answer: saturation region

QID : 520 - In semiconductors, ____________ depends upon both the electric field and carrier concentration.

1) diffusion current
2) drift current
3) drift velocity
4) both diffusion and drift current

Correct Answer: drift current

QID : 521 - Which operation is used in expression AB + BC + AC?

1) SOP
2) POS
3) OR
4) AND

Correct Answer: SOP

QID : 522 - Which of the following gate is a Universal gate?

1) AND
2) NAND
3) OR
4) XOR

Correct Answer: NAND

QID : 523 -

Correct Answer: 2

QID : 524 - Calculate the impedance (in Ohms) if the inductive reactance is 200 Ohms and resistance is 200 Ohms.

1) 220.15
2) 229.15
3) 250.45
4) 320.15

Correct Answer: 229.15

QID : 525 - What is the power factor in RLC series circuit below and above the resonant frequency respectively?

1) Both leading
2) Both lagging
3) Leading and lagging
4) Lagging and leading

Correct Answer: Leading and lagging

QID : 526 - What is the condition for maximum power delivered from source to its load?

1) Load resistance > Source resistance
2) Load resistance = Source resistance
3) Load resistance < Source resistance
4) Load resistance ≥ Source resistance

Correct Answer: Load resistance = Source resistance

QID : 527 - A bubble (small circle) on an input or output of a gate is equivalent to _________.

1) Adder
2) Subtractor
3) Inverter
4) Divider

Correct Answer: Inverter

QID : 528 - Which of the following is not capable of storing binary data?

1) Switch
2) Latch
3) Register
4) Counter

Correct Answer: Switch

QID : 529 - Which of the following counter is also called as asynchronous counter?

1) Decimal counter
2) Ripple counter
3) BCD counter
4) LSI counter

Correct Answer: Ripple counter

QID : 530 - What does the superposition theorem determines when it is applied to a linear network?

1) Frequency response
2) Power response
3) Current response
4) Current and voltage response

Correct Answer: Current and voltage response

QID : 531 - What is the value of current at resonance in RLC series circuit?

1) Maximum
2) Minimum
3) Zero
4) Infinite

Correct Answer: Maximum

QID : 532 - The full adder is a __________ input and _________ output combinational circuit.

1) 2 and 1
2) 2 and 2
3) 3 and 3
4) 3 and 2

Correct Answer: 3 and 2

QID : 533 - A down counter is a counter that counts from_________ to ________ in a downward direction.

1) 0 to 2 ^ n
2) 2 ^ n - 1 to 0
3) 0 to n
4) 0 to 2n - 1

Correct Answer: 2 ^ n - 1 to 0

QID : 534 - Which of the following statement is correct for 555 IC timers?

1) It operates in single mode
2) It operates in two modes
3) It operates in three modes
4) It operates in four modes

Correct Answer: It operates in three modes

QID : 535 - Which of the following represents 2's complement of 19?

1) {010111}
2) {100110}
3) {101010}
4) {101101}

Correct Answer: {101101}

QID : 536 - What is the main reason for using Yagi antenna?

1) High directivity
2) High gain
3) Low gain
4) Low directivity

Correct Answer: High gain

QID : 537 - The directivity of isotropic antenna is_____.

1) 0
2) 1
3) 1.5
4) 1.63

Correct Answer: 1

QID : 538 - In an antenna radiation pattern, a null is defined as a zone in which the ______________ is minimum.

1) gain
2) directivity
3) radiated power
4) return loss

Correct Answer: radiated power

QID : 539 - An antenna that radiates same power in all directions is called ____________.

1) Isotropic antenna
2) Parabolic antenna
3) Anisotropic antenna
4) Yagi-antenna

Correct Answer: Isotropic antenna

QID : 540 - Power density is defined as ____________ power per unit area.

1) refracted
2) reflected
3) radiated
4) diffracted

Correct Answer: radiated

QID : 541 - The performance of a system is degraded because of ___________.

1) losses
2) phase
3) amplitude
4) noise

Correct Answer: noise

QID : 542 - Which propagation does not operate above 30 MHZ?

1) Space wave propagation
2) Sky wave propagation
3) Ground wave propagation
4) Both ground and sky wave propagation

Correct Answer: Both ground and sky wave propagation

QID : 543 - The least distance between point of transmission and the point of reception is called _______.

1) Skip zone
2) Skip distance
3) Both skip zone and skip distance
4) None of the these

Correct Answer: Skip distance

QID : 544 - The value of modulation index (m) must be __________.

1) greater than 1
2) less than 1
3) in-between 0 and 1
4) 0

Correct Answer: less than 1

QID : 545 - Which of the following parameter remains same in the amplitude modulation?

1) Phase
2) Frequency
3) Amplitude
4) Frequency and phase

Correct Answer: Frequency and phase

QID : 546 - The radio waves are totally reflected back from the ionosphere at ___________.

1) cut-off frequency
2) critical frequency
3) optimum usable frequency
4) lowest usable frequency

Correct Answer: critical frequency

QID : 547 - What is the range of frequency for standard Amplitude Modulation broadcast?

1) 500 to 1500 kHz
2) 535 to 1605 kHz
3) 450 to 1600 kHz
4) 550 to 1605 kHz

Correct Answer: 535 to 1605 kHz

QID : 548 - Which signal gets easily affected by external atmosphere and electrical disturbances?

1) AM signals
2) FM signals
3) PM signals
4) PAM signal

Correct Answer: AM signals

QID : 549 - In QAM, there are two carrier signals. One is represented by _______ wave and other is represented by ________ wave.

1) sine and cosine
2) sine and tan
3) cosine and tan
4) sine and cosec

Correct Answer: sine and cosine

QID : 550 - What is the value of modulation index for AM wave if amplitude of modulating signal is 0.8 V and carrier amplitude is 2 V?

1) 0.2
2) 0.4
3) 0.5
4) 0.6

Correct Answer: 0.4

Study Kit for SSC Scientific Assistant (IMD) Examination

QID : 551 - When the phase angles of all the components of a given signal are shifted by ________, the resulting function of time is called the ‘Hilbert transform’ of signal.

Correct Answer: 3

QID : 552 - Which modulation technique uses the minimum channel bandwidth and transmitted power on its modulation?

1) FM
2) VSB
3) PM
4) SSB

Correct Answer: SSB

QID : 553 - The _____________ is the key circuit in Single-sideband generation.

1) Low pass filter
2) Envelope detector
3) Balanced modulator
4) Integrator

Correct Answer: Balanced modulator

QID : 554 - Calculate the total power transmitted if a carrier signal of 750 W, 2 MHz is amplitude modulated by a sinusoidal signal of 5 kHz to a depth of 50%.

1) 840.75 W
2) 843.70 W
3) 843.75 W
4) 850.75 W

Correct Answer: 843.75 W

QID : 555 - The process of recovering information signal from received carrier is known as ___________.

1) modulation
2) encoding
3) demodulator
4) sampling

Correct Answer: demodulator

QID : 556 - Which of the following is the medium of transmission of information in radio transmission?

1) An antenna
2) Co-axial cable
3) Space
4) Optical Fiber

Correct Answer: Space

QID : 557 - A carrier is frequency modulated by a sinusoidal modulating frequency of 2 kHz, resulting in frequency deviation of 5 kHz. What is the bandwidth occupied by the modulate waveform?

1) 10 kHz
2) 11 kHz
3) 14 kHz
4) 15 kHz

Correct Answer: 14 kHz

QID : 558 - For a narrow band FM, the bandwidth of the modulated signal is__________.

Correct Answer: 3

QID : 559 - FM signal is better than AM signal because ______________?

1) It is less immune to noise
2) It has less adjacent channel interference
3) Amplitude limiters are used to avoid amplitude variations
4) Less sensitivity

Correct Answer: It is less immune to noise

QID : 560 -

1) 10, 2308.9 Hz
2) 20, 1450.9 Hz
3) 10, 2000.0 Hz
4) 10, 2409.9 Hz

Correct Answer: 10, 2308.9 Hz

QID : 561 - What is the value of carrier swing of the FM signal of 100 kHz carrier frequency modulated by 5 kHz wave with frequency deviation of 150 kHz?

1) 150 kHz
2) 250 kHz
3) 300 kHz
4) 325 kHz

Correct Answer: 150 kHz

QID : 562 - Which of the property of carrier signal is varied with message signal at every symbol period in pulse amplitude modulation?

1) Frequency
2) Phase
3) Amplitude
4) Both frequency and phase

Correct Answer: Amplitude

QID : 563 - Which of the following is the frequency range of FM modulation?

1) 200-450 kHz
2) 88-108 MHz
3) 80-100 MHz
4) 540-1700 kHz

Correct Answer: 88-108 MHz

QID : 564 - The process of converting the Analog sample into discrete form is called __________.

1) modulation
2) demultiplexing
3) sampling
4) quatization

Correct Answer: quatization

QID : 565 - The main disadvantage of PM is __________.

1) high noise
2) it requires large bandwidth
3) cannot be decoded easily
4) complex

Correct Answer: it requires large bandwidth

QID : 566 - Which of the following is the expression for bandwidth of a PCM system?

Correct Answer: 1

QID : 567 - In a binary PCM system, if the level of pulses switches between –A/2 and A/2 then it is called a ___________ binary signal.

1) On-off
2) Polar
3) Bipolar
4) Unipolar

Correct Answer: Polar

QID : 568 - What is the bit rate (in kbps) generated by an ADC system with a sampling period of 0.5 millisecond and 20 bits/sample?

1) 40 kbps
2) 45 kbps
3) 50 kbps
4) 75 kbps

Correct Answer: 40 kbps

QID : 569 - What is the value of maximum slope in a delta modulation scheme with step height of 90 mV and step width of 2.5 ms that a staircase can track?

1) 36 V/s
2) 40 V/s
3) 46 V/s
4) 50 V/s

Correct Answer: 36 V/s

QID : 570 - What is the value of minimum sampling frequency of a signal passed through an LPF with cut-off frequency 20 kHz?

1) 20 kHz
2) 30 kHz
3) 40 kHz
4) 50 kHz

Correct Answer: 50 kHz

QID : 571 - __________ system provides the best tradeoff between bandwidth and S/N ratio.

1) PPM
2) PDM
3) PCM
4) PWM

Correct Answer: PCM

QID : 572 - Which one is used for the generation of a PWM (pulse width modulation) signal?

1) Integrator
2) Differentiator
3) An astable multivibrator
4) A monostable multivibrator

Correct Answer: A monostable multivibrator

QID : 573 - Calculate the total bit rate for the TDM link that has 30 signal channels sampled at 6 KHz and each sample is represented by 5 bits with one additional bit for synchronization.

1) 906 kbps
2) 960 kbps
3) 1000 kbps
4) 1068 kbps

Correct Answer: 906 kbps

QID : 574 - Which of the following techniques requires guard band?

1) FDM
2) TDM
3) PCM
4) PPM

Correct Answer: FDM

QID : 575 - In TDM, non-essential frequency components of the modulating signal are removed by _____________.

1) attenuator
2) sample
3) pre-alias filter
4) modulator

Correct Answer: pre-alias filter

QID : 576 - Calculate the baud rate of the ASK signal having the bit rate of 500 bps.

1) 100 bps
2) 250 bps
3) 300 bps
4) 500 bps

Correct Answer: 500 bps

QID : 577 - Which of the following techniques comes under the digital modulation techniques?

1) FM
2) PCM
3) FSK
4) ASK

Correct Answer: FM

QID : 578 - Phase locked loop and correlation receiver are used by __________.

1) ASK reception
2) FSK reception
3) PSK reception
4) Both ASK and PSK

Correct Answer: FSK reception

QID : 579 - Optical fiber operates in ___________.

1) ultraviolet band
2) infra red band
3) visible light band
4) ultraviolet, visible and infrared band

Correct Answer: ultraviolet, visible and infrared band

QID : 580 - Which of the following is the first commercial geostationary communication satellite?

1) ECHO
2) SPUTNIK
3) INTELSAT 1
4) INSAT 1A

Correct Answer: INTELSAT 1

QID : 581 - The probability of error for coherent FSK is ___________.

Correct Answer: 1

QID : 582 - In satellite communication, the uplink and downlink frequency for Ku band are_________ and _________, respectively.

1) 15 GHz; 10.9-12.75 GHz
2) 10 GHz; 10.9-12.55 GHz
3) 26.5-40 GHz; 18-20 GHz
4) 14 GHz; 10.9-12.75 GHz

Correct Answer: 14 GHz; 10.9-12.75 GHz

QID : 583 - Which of the following is the measuring device used in satellite communication?

1) Transponder
2) Payload
3) Apogee
4) Perigee

Correct Answer: Payload

QID : 584 - Calculate the EIRP (in dBw) of a satellite downlink at 15 GHz operates with a transmitting power of 5 watt and an antenna gain of 45.2 dB.

1) 42
2) 49
3) 50
4) 52

Correct Answer: 52

QID : 585 - The primary component of uplink section of satellite communication system is ________.

1) receiver
2) transformer
3) transistor
4) earth station transmitter

Correct Answer: earth station transmitter

QID : 586 - Calculate the effective resistance (in ohms) of an RLC resonant circuit has a resonance frequency of 2 MHz and a bandwidth of 10 KHz if the capacitance is 105 pF.

1) 2.87
2) 3.58
3) 3.78
4) 4.78

Correct Answer: 3.58

QID : 587 - What is the condition for series resonance to occur in a series resonance circuit?

Correct Answer: 4

QID : 588 - Which of the following element is absent in an active filter?

1) Resistor
2) Inductor
3) Capacitor
4) Both resistor and capacitor

Correct Answer: Inductor

QID : 589 - What is the main difference between first order LPF and second order LPF?

1) High cutoff frequency
2) Low cutoff frequency
3) Lower voltage gain
4) Higher voltage gain

Correct Answer: High cutoff frequency

QID : 590 - What is the main advantage of an active filter?

1) Do not offer gain
2) Easily tunable
3) Less complex
4) High impedance load

Correct Answer: Easily tunable

QID : 591 - In which type of connection we get neutral?

1) Star
2) Mesh
3) Delta
4) Both star and mesh

Correct Answer: Star

QID : 592 - For delta connection, the relationship between line voltage and phase voltage is ___________.

Correct Answer: 1

QID : 593 - Calculate the total number of loop equations of an electrical network with 12 loops and 8 nodes.

1) 4
2) 5
3) 6
4) 7

Correct Answer: 5

QID : 594 - What is the value of each resistance (in ohms) in delta representation with three resistance of 2 ohms each are connected in star form?

1) 0.6
2) 3.4
3) 3.5
4) 6

Correct Answer: 6

QID : 595 - What is the expression of resonant frequency in a series resonant circuit?

Correct Answer: 4

QID : 596 - Which of the following theorem is applicable to any active or passive network?

1) Thevenin's theorem
2) Tellegen’s theorem
3) Superposition theorem
4) Norton Theorem

Correct Answer: Tellegen’s theorem

QID : 597 -

1) 2 A and 2 Ohms
2) 0.71 A and 2.7 Ohms
3) 2.5 A and 1 Ohms
4) 1 A and 2 Ohms

Correct Answer: 0.71 A and 2.7 Ohms

QID : 598 - What is the relation between voltage across capacitor and voltage across inductor at resonance frequency?

1) Voltage across both is equal
2) Voltage across capacitor is less than voltage across inductor
3) Voltage across capacitor is greater than voltage across inductor
4) Voltage across capacitor is greater than or equal to voltage across inductor

Correct Answer: Voltage across both is equal

QID : 599 - Under which condition, a circuit is said to be in resonance?

1) Current is in phase with the applied voltage
2) Current is out of phase with the applied voltage
3) Current is 45 degree out of phase with the applied voltage
4) Current is 90 degree out of phase with the applied voltage

Correct Answer: Current is in phase with the applied voltage

QID : 600 -