Explore topic-wise MCQs in Engineering.

This section includes 9294 Mcqs, each offering curated multiple-choice questions to sharpen your Engineering knowledge and support exam preparation. Choose a topic below to get started.

8201.

The total field developed by an antenna array at a distant point is

A. phasor sum of fields produced by individual antennas of the array
B. algebraic sum of fields produced by individual antennas of the array
C. either (a) or (b) depending on type of array
D. neither (a) nor (b)
Answer» B. algebraic sum of fields produced by individual antennas of the array
Discussion
8202.

The magnitudes of OC and SC input impedances of a transmission line an 100 and 25 . The characteristic impedance is

A. 25
B. 50
C. 75
D. 100
Answer» C. 75
Discussion
8203.

In the given figure the reflected voltage wave after first reflection is

A. 18 V
B. -18 V
C. 30 V
D. -30 V
Answer» C. 30 V
Discussion
8204.

Assertion (A): A half wavelength line can be used as a 1 : 1 transformer.Reason (R): The input impedance of a half wavelength line is equal to load impedance.

A. Both A and R are correct and R is correct explanation of A
B. Both A and R are correct but R is not correct explanation of A
C. A is correct but R is wrong
D. A is wrong but R is correct
Answer» B. Both A and R are correct but R is not correct explanation of A
Discussion
8205.

A loss less line is terminated in a circular lines are E lines

A. SWR = 0
B. SWE = 0
C. SWR is finite
D. SWR =
Answer» D. SWR =
Discussion
8206.

A coaxial RF cable has a characteristic impedance of 50 and C equal to 40 pF/m. The inductance is

A. 1 H/m
B. 10 H/m
C. 0.1 H/m
D. 0.01 H/m
Answer» D. 0.01 H/m
Discussion
8207.

In a microwave coaxial line, the maximum operating frequency is f max and breakdown strength of dielectric is Ed' Then maximum power handling capacity is proportional to

A. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/18-214-1.png">
B. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/18-214-2.png">
C. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/18-214-3.png">
D. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/18-214-4.png">
Answer» C. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/18-214-3.png">
Discussion
8208.

To couple a coaxial line to a parallel wire line it is best to use

A. slotted line
B. balun
C. directional coupler
D. /4 transformer
Answer» C. directional coupler
Discussion
8209.

In a multicavity klystron amplifier the signal to be amplified develops an ac voltage of signal frequency across the gap in buncher cavity

A. True
B. False
Answer» B. False
Discussion
8210.

If VSWR is infinite, the transmission line is terminated in

A. short circuit
B. complex impedance
C. open circuit
D. either (a) or (c)
Answer» E.
Discussion
8211.

Roughly the time required for microwave cooking as compared to conventional cooking is

A. about twice
B. about half
C. about 10 times
D. about one-tenth
Answer» E.
Discussion
8212.

If the minimum range of a radar is to be doubled, the peak power has to be increased by a factor of

A. 2
B. 4
C. 8
D. 16
Answer» E.
Discussion
8213.

A magnetron requires an external magnetic field with flux lines parallel to axis of cathode

A. True
B. False
Answer» B. False
Discussion
8214.

When a line short circuited at far end, the minimum voltage occurs at

A. far end
B. source end
C. midway between source and far end
D. none of the above
Answer» B. source end
Discussion
8215.

In a TWT the axial component of electric field advances along the tube

A. at a velocity that is almost equal to speed of light
B. at a velocity that is a small fraction of speed of light
C. at a velocity that is about 50% of speed of light
D. at a velocity that may be even more than speed of light
Answer» C. at a velocity that is about 50% of speed of light
Discussion
8216.

Which one of the following is transferred locking electron device C antenna?

A. BARITT diode
B. IMPATT diode
C. Gunn diode
D. Step recovery diode
Answer» D. Step recovery diode
Discussion
8217.

If other parameter are constant, transmission loss at 5 GHz as compared to that at 0.5 GHz is

A. 20 dB more
B. 20 dB less
C. 700 dB more
D. 100 dB less
Answer» B. 20 dB less
Discussion
8218.

Assertion (A): Klystron amplifiers use one or more intermediate cavities in addition to buncher and catcher cavity.Reason (R): When one or more intermediate cavities are used the bandwidth can be increased.

A. Both A and R are correct and R is correct explanation of A
B. Both A and R are correct but R is not correct explanation of A
C. A is correct but R is wrong
D. A is wrong but R is correct
Answer» B. Both A and R are correct but R is not correct explanation of A
Discussion
8219.

A wave Em cos (bx - t) is a backward wave.

A. True
B. False
Answer» C.
Discussion
8220.

In a backward wave oscillator the wave

A. travelling along the line winds itself back and forth
B. progresses only in forward direction
C. progresses only in backward direction
D. either (a) or (c)
Answer» B. progresses only in forward direction
Discussion
8221.

A duplexer is used to

A. couple two antennas to a transmitter
B. isolate the antenna from the local oscillator
C. prevent interference between two antennas connected to receiver
D. use an antenna for reception or transmission without interference
Answer» E.
Discussion
8222.

A branched duplexer requires

A. TR tubes
B. ATR tube
C. both TR and ATR tube
D. none of the above
Answer» D. none of the above
Discussion
8223.

The directive gain of a transmitting antenna is

A. proportional to wavelength
B. inversely proportional to wavelength
C. proportional to square of wavelength
D. inversely proportional to square of wavelength
Answer» E.
Discussion
8224.

Assertion (A): The velocity factor of a line is the ratio of wave velocity on the line to speed of light.Reason (R): If the conductors of a line are immersed in a non magnetic insulating liquid, the wave velocity increases.

A. Both A and R are correct and R is correct explanation of A
B. Both A and R are correct but R is not correct explanation of A
C. A is correct but R is wrong
D. A is wrong but R is correct
Answer» D. A is wrong but R is correct
Discussion
8225.

Assertion (A): Magnetron is generally used in n mode.Reason (R): Frequency for p mode can be easily separated from adjacent modes.

A. Both A and R are correct and R is correct explanation of A
B. Both A and R are correct but R is not correct explanation of A
C. A is correct but R is wrong
D. A is wrong but R is correct
Answer» B. Both A and R are correct but R is not correct explanation of A
Discussion
8226.

A balun should have

A. low SWR at both ports
B. high SWR at both ports
C. high SWR at input port and low SWR at output port
D. low SWR at input port and high SWR at output
Answer» B. high SWR at both ports
Discussion
8227.

Thermal noise Power is

A. proportional to bandwidth (B)
B. B
C. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/539-1028-1.png">
D. B
E. <sup>2</sup>
Answer» B. B
Discussion
8228.

Consider the following statements: The radar pulse must be flat topped to allow accurate range measurementallow good minimum rangeprevent frequency changes in magnetronmake the returned echoes easier to distinguish from noise. Which of the above are correct?

A. 1, 2, 3, 4
B. 1, 2, 3
C. 1, 2
D. 1, 3, 4
Answer» C. 1, 2
Discussion
8229.

The characteristic impedance of coaxial cable is about

A. 1000 ohm
B. 500 ohm
C. 250 ohm
D. 75 ohm
Answer» E.
Discussion
8230.

The diameter and thickness of CD are

A. 6 cm and 1.2 mm
B. 6 cm and 0.6 mm
C. 12 cm and 0.6 mm
D. 12 cm and 1.2 mm
Answer» D. 12 cm and 1.2 mm
Discussion
8231.

Hue of a colour means

A. amount of light energy received by eye
B. predominant spectral purity of colour light
C. amount of other colours present
D. none of the above
Answer» C. amount of other colours present
Discussion
8232.

Filter method and phasing method are the methods for generating

A. SSB signal
B. vestigial side band signal
C. both SSB and vestigial sideband signals
D. none of the above
Answer» B. vestigial side band signal
Discussion
8233.

Which one the following is an advantage of AM over FM?

A. FM has wide bandwidth
B. FM has better
C. FM is more immune to noise
D. Probability of noise spike generation is less in AM
Answer» E.
Discussion
8234.

A typical value of insertion loss of SAW filter is

A. 15 dB
B. 2 dB
C. 40 dB
D. 60 dB
Answer» B. 2 dB
Discussion
8235.

In a superheterodyne radio receiver

A. RF amplifier normally operates at 455 kHz above carrier frequency
B. mixer input must be tuned to the signal frequency
C. local oscillator operates below signal frequency
D. local oscillator frequency is double the IF
Answer» C. local oscillator operates below signal frequency
Discussion
8236.

In phase modulation, the phase deviation is

A. proportional to the amplitude of the signal and varies with frequency
B. remains constant while amplitude and frequency of signal varies
C. proportional to the amplitude of the signal and independent of the frequency
D. none of the above
Answer» D. none of the above
Discussion
8237.

The assigned carrier frequency of an FM broadcast station is 96.3 MHz. Its FM signal has a centre frequency of

A. 10 MHz
B. 455 kHz
C. 48.15 MHz
D. 96.3 MHz
Answer» E.
Discussion
8238.

Digital television is also called

A. High digital television
B. High definition television
C. High deflection television
D. High display television
Answer» C. High deflection television
Discussion
8239.

The number of spectral component of a cosine wave is

A. 1
B. 0
C. 2
D. 4
Answer» D. 4
Discussion
8240.

Consider the following statements about advantages of phase discriminator over slope detector Fewer tuned circuitsGreater limitingBetter linearityEasy alignment Which of the above are true?

A. 1, 2, 3, 4
B. 2, 3, 4
C. 1, 2, 3
D. 1, 3, 4
Answer» E.
Discussion
8241.

If a signal band limited for fm is sampled at a rate less than 2 fm the reconstructed signal will be

A. smaller in amplitude
B. distorted
C. having higher frequencies suppressed
D. none of the above
Answer» C. having higher frequencies suppressed
Discussion
8242.

A better SNR can be obtained in a PCM by

A. increasing sampling rate above Nyquist rate
B. decreasing the code bits
C. reducing channel bandwidth
D. increasing Quantization levels
Answer» E.
Discussion
8243.

In communication systems, the modulating signal is also called

A. base band signal
B. side bands
C. auxiliary signal
D. none of the above
Answer» B. side bands
Discussion
8244.

The type of noise that interfere very much with high frequency transmission is

A. white
B. transit time
C. flicker
D. shot
Answer» C. flicker
Discussion
8245.

For a parallel two wire line with both conductors touching each other, the characteristic impedance is about

A. 300 &ohm;
B. 200 &ohm;
C. 80 &ohm;
D. 24 &ohm;
Answer» D. 24 &ohm;
Discussion
8246.

TV receivers use flyback switched mode power supply because

A. it can supply many voltage outputs
B. it does not require a filter choke and is cheap
C. it has very good regulation at all loads
D. both (a) and (c)
Answer» C. it has very good regulation at all loads
Discussion
8247.

Assertion (A): In SSB, carrier is suppressed by about 45 dB Reason (R): SSB is standard form for radio communication

A. Both A and R are correct and R is correct explanation of A
B. Both A and R are correct but R is not correct explanation of A
C. A is correct but R is wrong
D. A is wrong but R is correct
Answer» C. A is correct but R is wrong
Discussion
8248.

SSB stands for

A. Single Side Band
B. Suppressed Side Band
C. Single Sound Band
D. Single Sky Band
Answer» B. Suppressed Side Band
Discussion
8249.

Tape recorders use

A. cone type loudspeakers
B. horn type loudspeakers
C. either cone type or horn type loudspeakers
D. none of the above
Answer» B. horn type loudspeakers
Discussion
8250.

Which of the following is Doppler effect not used?

A. CW radar
B. FM radar
C. MTI system
D. Moving target plotting on PPI
Answer» E.
Discussion