A geosynchronous satellite

has the same period a that of the Earth

rotates in the equatorial plane

A duplexer is a device used to

feed more than one receiver from a single antenna

connect two transmitters to the same antenna

connect a receiver and a transmitter to the same antenna

The discussing sharing of a communication satellite by many geographically dispersed Earth station, DAMA means

Decibel Attenuated Microwave Access

Demand-Assigned Multiple Access

Decibel Attenuated Microwave Access

Dynamically-Assigned Multiple Access

It is known that noise phase modulates the FM wave. As the noise side band frequency approaches the carrier frequency, the noise amplitude

will reduce to negligible value

In a broadcast superheterodyne receiver

the local oscillator operates below the signal frequency

local oscillator frequency is normally double the IF

RF amplifier normally works at kHz above the carrier frequency

mixer input must be tuned to the signal frequency

whenever a flip flop sets to 0, the next higher FF remains unchanged

whenever a flip flop sets to 1, the next higher FF toggles

whenever a flip flop sets to 0, the next higher FF remains unchanged

whenever a flip flop sets to 1, the next higher FF faces race condition

whenever a flip flop sets to 0, the next higher FF faces race condition

Assertion (A): Inverters and choppers use fast switching thyristors Reason (R): Fast switching SCR has low turn off time.

Both A and R correct but R is not correct explanation of A

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

The value of capacitor C for dynamic equalising circuit of series connected thyristors is determined by

both forward and reverse recovery characteristics of thyristors

forward characteristics of thyristors

reverse recovery characteristics of thyristors

both forward and reverse recovery characteristics of thyristors

converts ac of one frequency into ac of another frequency

converts constant voltage dc into ac and then into variable voltage dc

converts constant voltage dc into variable voltage dc directly

converts ac of one frequency into ac of another frequency

Assertion (A): If the duty cycle of chopper is low the current would not become discontinuousReason (R): If the time constant L/R of the load in chopper is low the current may become discontinuous.

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

The phenomenon of overlap in converter operation due to

both source resistance and source inductance

An SCR is triggered at 40 in the positive half cycle only. The average anode current is 50 A. If the firing angle is changed to 80 , the average anode current is likely to be

less than 50 A but more than 25 A

In a superheterodyne receiver

the RF stage has better selectivity than IF stage

the IF stage has better selectivity than RF stage

the RF stage has better selectivity than IF stage

the RF stage has same selectivity than IF stage

An OR gate has 4 inputs. One input is high and the other three are low. The output

may be high or low depending on relative magnitude of inputs

Two thyristor of same rating and same specifications

will have unequal turn on and turn off periods

will have equal turn on and turn off periods

will have equal turn on but unequal turn off periods

may have equal or unequal turn on and turn off periods

will have unequal turn on and turn off periods

The function f(x - vot) represent which of the following?

A wave motion in reverse direction

A wave motion in forward direction

A wave motion in reverse direction

9294 + Mcqs in Electronics and Communication Engineering in Engineering Page 2 McqOptions

51.	A geosynchronous satellite
A.	has the same period a that of the Earth
B.	has a circular orbit
C.	rotates in the equatorial plane
D.	has all of the above
Answer» E.

Discussion

52.	Neutralization is used in RF amplifiers to
A.	stop oscillation
B.	increase bandwidth
C.	improve selectivity
D.	all of the above
Answer» B. increase bandwidth

Discussion

53.	The angle subtended by earth at geostationary communication satellite is
A.	17.34
B.	51.4
C.	120
D.	60
Answer» B. 51.4

Discussion

54.	Which are the popular IF frequencies for microwave and radar receivers operating on frequencies in the range 1 to 10 GHz
A.	30, 60 and 70 kHz
B.	3, 6 and 7 kHz
C.	30, 60 and 70 MHz
D.	3, 6 and 7 GHz
Answer» D. 3, 6 and 7 GHz

Discussion

55.	A duplexer is a device used to
A.	feed more than one receiver from a single antenna
B.	connect two transmitters to the same antenna
C.	connect a receiver and a transmitter to the same antenna
D.	none of these
Answer» D. none of these

Discussion

56.	The discussing sharing of a communication satellite by many geographically dispersed Earth station, DAMA means
A.	Demand-Assigned Multiple Access
B.	Decibel Attenuated Microwave Access
C.	Digital Analog Master Antenna
D.	Dynamically-Assigned Multiple Access
Answer» B. Decibel Attenuated Microwave Access

Discussion

57.	It is known that noise phase modulates the FM wave. As the noise side band frequency approaches the carrier frequency, the noise amplitude
A.	will increase
B.	will decrease
C.	will remain constant
D.	will reduce to negligible value
Answer» C. will remain constant

Discussion

58.	In a broadcast superheterodyne receiver
A.	the local oscillator operates below the signal frequency
B.	local oscillator frequency is normally double the IF
C.	RF amplifier normally works at kHz above the carrier frequency
D.	mixer input must be tuned to the signal frequency
Answer» E.

Discussion

59.	A JK flip flop has t_pd= 12 ns. The largest modulus of a ripple counter using these flip flops and operating at 10 MHz is
A.	16
B.	64
C.	128
D.	256
Answer» E.

Discussion

60.	The basic storage element in a digital system is
A.	flip flop
B.	counter
C.	multiplexer
D.	encoder
Answer» B. counter

Discussion

61.	The access time of a word in 4 MB main memory is 100 ms. The access time of a word in a 32 kb data cache memory is 10 ns. The average data cache bit ratio is 0.95. The efficiency of memory access time is
A.	9.5 ns
B.	14.5 ns
C.	20 ns
D.	95 ns
Answer» C. 20 ns

Discussion

62.	The expression Y = pM (0, 1, 3, 4) is
A.	POS
B.	SOP
C.	Hybrid
D.	none of the above
Answer» B. SOP

Discussion

63.	An 8 bit DAC has a full scale output of 2 mA and full scale error of 0.5%. If input is 10000000 the range of outputs is
A.	994 to 1014 A
B.	990 to 1020 A
C.	800 to 1200 A
D.	none of the above
Answer» B. 990 to 1020 A

Discussion

64.	Decimal 43 in hexadecimal and BCD number system is respectively.
A.	B2, 01000011
B.	2B, 01000011
C.	2B, 00110100
D.	B2, 01000100
Answer» C. 2B, 00110100

Discussion

65.	In a ripple counter,
A.	whenever a flip flop sets to 1, the next higher FF toggles
B.	whenever a flip flop sets to 0, the next higher FF remains unchanged
C.	whenever a flip flop sets to 1, the next higher FF faces race condition
D.	whenever a flip flop sets to 0, the next higher FF faces race condition
Answer» B. whenever a flip flop sets to 0, the next higher FF remains unchanged

Discussion

66.	In a step down chopper using pulse width modulation, T_on = 3 x 10^-3 and T_off = 1 x 10^-3 s. The chopping frequency is
A.	333.33
B.	250
C.	500
D.	1000
Answer» C. 500

Discussion

67.	Thyristors are suitable for dc circuit breakers but not for ac circuit breakers.
A.	True
B.	False
Answer» C.

Discussion

68.	Assertion (A): Inverters and choppers use fast switching thyristors Reason (R): Fast switching SCR has low turn off time.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R 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 correct but R is not correct explanation of A

Discussion

69.	The value of capacitor C for dynamic equalising circuit of series connected thyristors is determined by
A.	forward characteristics of thyristors
B.	reverse recovery characteristics of thyristors
C.	both forward and reverse recovery characteristics of thyristors
D.	none of the above
Answer» C. both forward and reverse recovery characteristics of thyristors

Discussion

70.	A chopper
A.	converts constant voltage dc into ac and then into variable voltage dc
B.	converts constant voltage dc into variable voltage dc directly
C.	converts ac of one frequency into ac of another frequency
D.	converts ac to dc
Answer» C. converts ac of one frequency into ac of another frequency

Discussion

71.	Assertion (A): If the duty cycle of chopper is low the current would not become discontinuous Reason (R): If the time constant L/R of the load in chopper is low the current may become discontinuous.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R 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

72.	In a single phase full wave regulator, the firing angles in the positive and negative half cycles are generally
A.	equal
B.	different
C.	equal or different
D.	different but sometimes equal
Answer» B. different

Discussion

73.	An electric heater is controlled by thyristors through on-off control. If a = 0.4, the heating is
A.	16% maximum
B.	40% of maximum
C.	60% of maximum
D.	84% of maximum
Answer» C. 60% of maximum

Discussion

74.	A semiconverter feeding an RLE load operates in
A.	first quadrant only
B.	first and second quadrants
C.	first and fourth quadrants
D.	first and third quadrants
Answer» B. first and second quadrants

Discussion

75.	The phenomenon of overlap in converter operation due to
A.	source resistance
B.	source inductance
C.	both source resistance and source inductance
D.	high value of firing angle
Answer» C. both source resistance and source inductance

Discussion

76.	A thyristor has a maximum allowable junction temperature of 120 C and the ambient temperature is 40 C. If thermal resistance is 1.6 C/W, the maximum allowable internal power dissipation is
A.	20 W
B.	50 W
C.	92 W
D.	128 W
Answer» C. 92 W

Discussion

77.	The terminals of a power BJT are called
A.	emitter, base, collector
B.	emitter, base, drain
C.	source, base, drain
D.	source, base, collector
Answer» B. emitter, base, drain

Discussion

78.	In single phase half wave regulator, the average current over one full cycle
A.	is always positive
B.	may be positive or negative
C.	may be negative
D.	is always negative
Answer» E.

Discussion

79.	An SCR is triggered at 40 in the positive half cycle only. The average anode current is 50 A. If the firing angle is changed to 80 , the average anode current is likely to be
A.	50 A
B.	25 A
C.	less than 50 A but more than 25 A
D.	less than 25 A
Answer» D. less than 25 A

Discussion

80.	A rectangular metal waveguide filled with a dielectric of relative permittivity _r = 4, has the inside dimensions 3 x 1.2 cm, the cut off frequency for the dominant mode is
A.	2.5 GHz
B.	5 GHz
C.	10 GHz
D.	12.5 GHz
Answer» C. 10 GHz

Discussion

81.	Noise temperature of Sun is more than __________ K.
A.	1000
B.	5000
C.	100000
D.	500
Answer» D. 500

Discussion

82.	The function of an AM detector circuit is to
A.	rectify the input signal
B.	discard the carrier
C.	provide audio signal
D.	all of the above
Answer» E.

Discussion

83.	In a superheterodyne receiver
A.	the IF stage has better selectivity than RF stage
B.	the RF stage has better selectivity than IF stage
C.	the RF stage has same selectivity than IF stage
D.	none of the above
Answer» B. the RF stage has better selectivity than IF stage

Discussion

84.	Most popular IF for receivers tuning to 540 to 1650 kHz is
A.	433 kHz
B.	455 kHz
C.	545 kHz
D.	555 kHz
Answer» C. 545 kHz

Discussion

85.	The resolution of an n bit DAC with a maximum input of 5 V is 5 mV. The value of n is
A.	8
B.	9
C.	10
D.	11
Answer» D. 11

Discussion

86.	2's complement of binary number 0101 is
A.	1011
B.	1111
C.	1101
D.	1110
Answer» B. 1111

Discussion

87.	An OR gate has 4 inputs. One input is high and the other three are low. The output
A.	is low
B.	is high
C.	is alternately high and low
D.	may be high or low depending on relative magnitude of inputs
Answer» C. is alternately high and low

Discussion

88.	Decimal number 10 is equal to binary number
A.	1110
B.	1010
C.	1001
D.	1000
Answer» C. 1001

Discussion

89.	Both OR and AND gates can have only two inputs.
A.	True
B.	False
Answer» C.

Discussion

90.	In the below figure the average load current is 15 A. The rms value of transformer secondary current is
A.	15 A
B.	10.61 A
C.	7.5 A
D.	14.14 A
Answer» C. 7.5 A

Discussion

91.	In a 3 phase fully controlled converter the firing frequency is
A.	3 times the line frequency
B.	6 times the line frequency
C.	9 times the line frequency
D.	12 times the line frequency
Answer» C. 9 times the line frequency

Discussion

92.	Two thyristor of same rating and same specifications
A.	will have equal turn on and turn off periods
B.	will have equal turn on but unequal turn off periods
C.	may have equal or unequal turn on and turn off periods
D.	will have unequal turn on and turn off periods
Answer» D. will have unequal turn on and turn off periods

Discussion

93.	The amount of dielectric heating is inversely proportional to frequency.
A.	True
B.	False
Answer» C.

Discussion

94.	Z_L = 200 &ohm; and it is desired that Z_i = 50 &ohm; The quarter wave transformer should have a characteristic impedance of
A.	100 &ohm;
B.	40 &ohm;
C.	10000 &ohm;
D.	4 &ohm;
Answer» B. 40 &ohm;

Discussion

95.	A broadside array consisting of 200 cm wavelength with 10 half-wave dipole spacing 10 cm. And if each array element feeding with 1 amp. current and operating at same frequency then find the half power beamwidth
A.	4
B.	2
C.	10
D.	15
Answer» C. 10

Discussion

96.	Refractive index of glass is 1.5. Find the wavelength of a beam of light with a frequency of 10¹⁴ Hz in glass. Assume velocity of light is 3 x 10⁸ m/sec in vacuum.
A.	4 m
B.	3 m
C.	2 m
D.	1 m
Answer» D. 1 m

Discussion

97.	The function f(x - v_ot) represent which of the following?
A.	A stationary wave
B.	A wave motion in forward direction
C.	A wave motion in reverse direction
D.	None of the above
Answer» C. A wave motion in reverse direction

Discussion

98.	A broadside array operating at 100 cm wavelength consist of 4 half-wave dipoles spaced 50 cm apart. Each element carries radio frequency current in the same phase and of magnitude 0.5 A. The radiated power will be
A.	196 W
B.	73 W
C.	36.5 W
D.	18.25 W
Answer» B. 73 W

Discussion

99.	If and A + B is
A.	<img src="/_files/images/electronics-and-communication-engineering/signals-and-systems/13-165-1.png">
B.	<img src="/_files/images/electronics-and-communication-engineering/signals-and-systems/13-165-2.png">
C.	<img src="/_files/images/electronics-and-communication-engineering/signals-and-systems/13-165-3.png">
D.	<img src="/_files/images/electronics-and-communication-engineering/signals-and-systems/13-165-4.png">
Answer» B. <img src="/_files/images/electronics-and-communication-engineering/signals-and-systems/13-165-2.png">

Discussion

100.	A voltage V(t) is a Gaussian ergodic random process with a mean of zero and a variance of 4 volt². If it is measured by a dc meter. The reading will be
A.	0
B.	4
C.	2
D.	<span class="root">2</span>
Answer» B. 4

Discussion

Explore topic-wise MCQs in Engineering.

A geosynchronous satellite

Neutralization is used in RF amplifiers to

The angle subtended by earth at geostationary communication satellite is

Which are the popular IF frequencies for microwave and radar receivers operating on frequencies in the range 1 to 10 GHz

A duplexer is a device used to

The discussing sharing of a communication satellite by many geographically dispersed Earth station, DAMA means

It is known that noise phase modulates the FM wave. As the noise side band frequency approaches the carrier frequency, the noise amplitude

In a broadcast superheterodyne receiver

A JK flip flop has tpd= 12 ns. The largest modulus of a ripple counter using these flip flops and operating at 10 MHz is

The basic storage element in a digital system is

The access time of a word in 4 MB main memory is 100 ms. The access time of a word in a 32 kb data cache memory is 10 ns. The average data cache bit ratio is 0.95. The efficiency of memory access time is

The expression Y = pM (0, 1, 3, 4) is

An 8 bit DAC has a full scale output of 2 mA and full scale error of 0.5%. If input is 10000000 the range of outputs is

Decimal 43 in hexadecimal and BCD number system is respectively.

In a ripple counter,

In a step down chopper using pulse width modulation, Ton = 3 x 10-3 and Toff = 1 x 10-3 s. The chopping frequency is

Thyristors are suitable for dc circuit breakers but not for ac circuit breakers.

Assertion (A): Inverters and choppers use fast switching thyristors Reason (R): Fast switching SCR has low turn off time.

The value of capacitor C for dynamic equalising circuit of series connected thyristors is determined by

A chopper

Assertion (A): If the duty cycle of chopper is low the current would not become discontinuousReason (R): If the time constant L/R of the load in chopper is low the current may become discontinuous.

In a single phase full wave regulator, the firing angles in the positive and negative half cycles are generally

An electric heater is controlled by thyristors through on-off control. If a = 0.4, the heating is

A semiconverter feeding an RLE load operates in

The phenomenon of overlap in converter operation due to

A thyristor has a maximum allowable junction temperature of 120 C and the ambient temperature is 40 C. If thermal resistance is 1.6 C/W, the maximum allowable internal power dissipation is

The terminals of a power BJT are called

In single phase half wave regulator, the average current over one full cycle

An SCR is triggered at 40 in the positive half cycle only. The average anode current is 50 A. If the firing angle is changed to 80 , the average anode current is likely to be

A rectangular metal waveguide filled with a dielectric of relative permittivity r = 4, has the inside dimensions 3 x 1.2 cm, the cut off frequency for the dominant mode is

Noise temperature of Sun is more than __________ K.

The function of an AM detector circuit is to

In a superheterodyne receiver

Most popular IF for receivers tuning to 540 to 1650 kHz is

The resolution of an n bit DAC with a maximum input of 5 V is 5 mV. The value of n is

2's complement of binary number 0101 is

An OR gate has 4 inputs. One input is high and the other three are low. The output

Decimal number 10 is equal to binary number

Both OR and AND gates can have only two inputs.

In the below figure the average load current is 15 A. The rms value of transformer secondary current is

In a 3 phase fully controlled converter the firing frequency is

Two thyristor of same rating and same specifications

The amount of dielectric heating is inversely proportional to frequency.

ZL = 200 &ohm; and it is desired that Zi = 50 &ohm; The quarter wave transformer should have a characteristic impedance of

A broadside array consisting of 200 cm wavelength with 10 half-wave dipole spacing 10 cm. And if each array element feeding with 1 amp. current and operating at same frequency then find the half power beamwidth

Refractive index of glass is 1.5. Find the wavelength of a beam of light with a frequency of 1014 Hz in glass. Assume velocity of light is 3 x 108 m/sec in vacuum.

The function f(x - vot) represent which of the following?

A broadside array operating at 100 cm wavelength consist of 4 half-wave dipoles spaced 50 cm apart. Each element carries radio frequency current in the same phase and of magnitude 0.5 A. The radiated power will be

If and A + B is

A voltage V(t) is a Gaussian ergodic random process with a mean of zero and a variance of 4 volt2. If it is measured by a dc meter. The reading will be

A JK flip flop has t_pd= 12 ns. The largest modulus of a ripple counter using these flip flops and operating at 10 MHz is

In a step down chopper using pulse width modulation, T_on = 3 x 10^-3 and T_off = 1 x 10^-3 s. The chopping frequency is

Assertion (A): Inverters and choppers use fast switching thyristors
Reason (R): Fast switching SCR has low turn off time.

Assertion (A): If the duty cycle of chopper is low the current would not become discontinuous
Reason (R): If the time constant L/R of the load in chopper is low the current may become discontinuous.

A rectangular metal waveguide filled with a dielectric of relative permittivity _r = 4, has the inside dimensions 3 x 1.2 cm, the cut off frequency for the dominant mode is

Z_L = 200 &ohm; and it is desired that Z_i = 50 &ohm; The quarter wave transformer should have a characteristic impedance of

Refractive index of glass is 1.5. Find the wavelength of a beam of light with a frequency of 10¹⁴ Hz in glass. Assume velocity of light is 3 x 10⁸ m/sec in vacuum.

The function f(x - v_ot) represent which of the following?

A voltage V(t) is a Gaussian ergodic random process with a mean of zero and a variance of 4 volt². If it is measured by a dc meter. The reading will be