Explore topic-wise MCQs in Testing Subject.

This section includes 657 Mcqs, each offering curated multiple-choice questions to sharpen your Testing Subject knowledge and support exam preparation. Choose a topic below to get started.

1.

Assertion (A): Microstrip is very commonly used in microwave integrated circuits.Reason (R): Microstrip has an easy access to the top-surface so that active and passive discrete components can be easily mounted.

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
2.

In a TWT the amplitude of resultant wave travelling down the helix remains constant

A. True
B. False
Answer» C.
Discussion
3.

In the given figure forward current wave has a magnitude of

A. 0.45 A
B. 0.3 A
C. 0.2 A
D. 0.1 A
Answer» C. 0.2 A
Discussion
4.

In an infinite line the input impedance at every point is equal to characteristic impedance.

A. True
B. False
Answer» B. False
Discussion
5.

Consider the following time parameters Domain growth time constant.Transit time.Dielectric relaxation time in positive mobility regime. Which of the above are used in connection width transferred electron device?

A. 1, 2, and 3
B. 1 and 2 only
C. 1 and 3 only
D. 2 and 3 only
Answer» B. 1 and 2 only
Discussion
6.

A disadvantage of microstrip line as the connections of compared to strip line is that former

A. do not lend themselves to printed circuit
B. are more likely to radiate
C. are bulky
D. are more expensive and complex
Answer» C. are bulky
Discussion
7.

As frequency increases, the transmission efficiency

A. decreases
B. increases
C. is not affected
D. either (a) or (c)
Answer» C. is not affected
Discussion
8.

The directive gain of a transmitting antenna is proportional to

A. its cross-sectional area
B. square of cross-sectional area
C. square root of cross-sectional area
D. cube root of cross-sectional area
Answer» B. square of cross-sectional area
Discussion
9.

In a loss line RL < Z0, then

A. Reflection coefficient is zero
B. Reflection coefficient is
C. Reflection coefficient is negative
D. Reflection coefficient is positive
Answer» D. Reflection coefficient is positive
Discussion
10.

Assertion (A): A backward wave oscillator can be used as a sweep generator.Reason (R): The frequency of oscillation of a backward wave oscillator can be changed by varying the voltage which controls the beam velocity.

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
11.

The correct sequence of parts in klystron amplifier are

A. anode, catcher cavity, cathode, buncher cavity
B. cathode, buncher cavity, catcher cavity, cavity
C. anode, buncher cavity, catcher cavity, cathode
D. cathode, catcher cavity, anode, buncher cavity
Answer» C. anode, buncher cavity, catcher cavity, cathode
Discussion
12.

The electric field in a TWT due to applied signal

A. is directed along the helix axis
B. is directed radially from helix axis
C. is inclined to the helix axis by about 60
D. is inclined to the helix axis by about 45
Answer» B. is directed radially from helix axis
Discussion
13.

In a line with finite attenuation

A. power transmission is least efficient when there are no standing waves on the line
B. power transmission is most efficient when there are no standing waves on line
C. Load power depends on phase constant
D. standing waves will always exist on the line
Answer» C. Load power depends on phase constant
Discussion
14.

A radar has a maximum range of 120 km. The maximum allowable pulse repetition frequency for unambiguous reception is

A. 1250
B. 330
C. 2500
D. 8330
Answer» B. 330
Discussion
15.

The cut off wavelength in circular waveguide

A. guide diameter
B. square of guide diameter
C. cube of guide diameter
D. square root of guide diameter
Answer» B. square of guide diameter
Discussion
16.

In Reflex Klystron oscillator the focussing electrode is at a high potential

A. True
B. False
Answer» C.
Discussion
17.

If antenna diameter is increased four times, the maximum range is increased by a factor of

A. <span class="root">2</span>
B. 2
C. 4
D. 0.2
Answer» D. 0.2
Discussion
18.

Assertion (A): Gunn diode is a transferred electron device.Reason (R): A Gunn oscillator uses the phenomenon of transferred electron effect.

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
19.

A cavity resonator is

A. a hollow metallic enclosure
B. a hollow enclosure having magnetic material as its walls
C. a hollow enclosure having dielectric material as its walls
D. either (b) or (c)
Answer» B. a hollow enclosure having magnetic material as its walls
Discussion
20.

The skin depth at 1000 MHz as compared to that at 500 MHz is

A. 2
B. 12
C. 0.707
D. 0.5
Answer» D. 0.5
Discussion
21.

The HV and other voltage supplies for a TV receiver are obtained from IHVT. The full name for this device is

A. Internal high voltage transformer
B. Integrated high voltage transformer
C. Instant high voltage transformer
D. Interleaved high voltage transformer
Answer» C. Instant high voltage transformer
Discussion
22.

An antenna operates effectively when its dimensions are

A. of the order of magnitude of wavelength to be transmitted
B. very small than the magnitude of wavelength to be transmitted
C. very large than the magnitude of wavelength to be transmitted
D. either (a) or (b)
Answer» B. very small than the magnitude of wavelength to be transmitted
Discussion
23.

The main systems used for generation of SSB are

A. filter method
B. phase cancellation method
C. third method
D. all of the above
Answer» E.
Discussion
24.

In a pulsed RADAR typical value of pulse duration and pulse frequency respectively are

A. 1 s and 50 Hz
B. 1 s and 500 Hz
C. 4 s and 50 Hz
D. 4 s and 500 Hz
Answer» C. 4 s and 50 Hz
Discussion
25.

The mobile unit of a mobile telephone is generally in

A. vehicles
B. pocket
C. office
D. vehicle or pocket
Answer» B. pocket
Discussion
26.

Assertion (A): Water waves are longitudinal but EM waves are transverseReason (R): In an EM wave electric field, magnetic field and propagation are mutually perpendicular.

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
27.

In the human eye, an image persists for a time of about

A. 1 second
B. 0.1 second
C. 0.05 second
D. 0.02 second
Answer» E.
Discussion
28.

The different channels in a TDM receiver are separated by

A. integration
B. differentiation
C. AND gate
D. OR gate
Answer» D. OR gate
Discussion
29.

In a hi-fi system the nonlinear distortion should be less than

A. 10%
B. 5%
C. 2%
D. 1%
Answer» E.
Discussion
30.

A pure tone at 1000 Hz has a dB level of 50 dB. If two such tones exist simultaneously the dB level is about

A. 50 dB
B. 53 dB
C. 100 dB
D. 200 dB
Answer» C. 100 dB
Discussion
31.

At FM demodulator output noise power density

A. increases with frequency
B. decreases with frequency
C. remains unaltered
D. none of the above
Answer» B. decreases with frequency
Discussion
32.

According to CCIR standards, the Vestigial Sideband (VSB)

A. video frequencies upto 4 MHz are transmitted
B. video frequencies upto 5 MHz are transmitted
C. video frequencies upto 5.5 MHz are transmitted
D. video frequencies upto 6 MHz are transmitted
Answer» C. video frequencies upto 5.5 MHz are transmitted
Discussion
33.

Line of sight transmission is used in

A. radio frequencies below 1 MHz
B. VHF only
C. audio signals only
D. VHF and UHF
Answer» E.
Discussion
34.

Some multiplexing arrangements for telephone system are Space multiplexingTime division multiplexingFrequency division multiplexing Which of the above allow transmission of many independent signals over a single channel?

A. 1 only
B. 2 and 3 only
C. 1, 2, 3
D. 1 and 3 only
Answer» C. 1, 2, 3
Discussion
35.

Industrial noise has the frequency range of

A. 1 to 100 Hz
B. 200 to 5000 Hz
C. above 200 MHz
D. 1 to 600 MHz
Answer» E.
Discussion
36.

In a circular waveguide TE21 mode has lowest cutoff frequency

A. True
B. False
Answer» C.
Discussion
37.

The number of TV channels which can be accommodated in a spectrum of 300 MHz is about

A. 5
B. 10
C. 50
D. 200
Answer» D. 200
Discussion
38.

The noise figure of multicavity klystron amplifier is very low

A. True
B. False
Answer» C.
Discussion
39.

In the given figure the E and H lines in a coaxial cable

A. The radial lines are E lines and circular lines are H lines
B. Radial lines are H lines and circular lines are E lines
C. The directions of E and H lines are wrong
D. Radial lines may be E and H lines depending an direction of current
Answer» B. Radial lines are H lines and circular lines are E lines
Discussion
40.

Assertion (A): The velocity of electromagnetic waves on overhead lines and coaxial cables is the same.Reason (R): Free space has an intrinsic impedance of 377 ohms.

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» E.
Discussion
41.

The main feature of a parametric amplifier is

A. low noise
B. very high gain
C. broad bandwidth
D. both (b) and (c)
Answer» D. both (b) and (c)
Discussion
42.

Assertion (A): PIN diode is commonly used for microwave control.Reason (R): A PIN diode uses heavily doped p and n materials.

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
43.

In a vacuum tube, the transit time of electron between cathode and anode is important at

A. low frequencies
B. high frequencies
C. both (a) and (b)
D. frequencies which are neither very low nor very high
Answer» C. both (a) and (b)
Discussion
44.

A coaxial line has L = 500 nH/m and C = 50 pF/m. The characteristic impedance is

A. 500
B. 250
C. 100
D. 50
Answer» D. 50
Discussion
45.

Assertion (A): A line of length and short circuited at far end has an input impedance of infinity.Reason (R): A line of length and short circuited at far end behaves as a parallel resonant circuit.

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
46.

Assertion (A): A quarter wave transformer is used to match a resistive load to a transmission line.Reason (R): A quarter wave transformer is a transmission line of quarter wave length.

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
47.

Which of the following terminations makes the input impedance of a line equal to characteristic impedance Z0?

A. line open circuited at far end
B. line terminated in Z
C. <sub>0</sub>
D. line short circuited at far end
E. line terminated in inductance
Answer» C. <sub>0</sub>
Discussion
48.

High speed logic circuits use

A. pulses with very small width
B. pulses with very large width
C. pulses whose width is neither small nor large
D. either (b) or (c)
Answer» B. pulses with very large width
Discussion
49.

In microwave system the function of mode filter is

A. to suppress modes with lower cut off frequencies
B. to suppress modes with higher cut off frequencies
C. to change mode of wave transmission
D. both (b) and (c)
Answer» E.
Discussion
50.

For the strip line in the given figure the capacitance per unit length =

A. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/19-216-1.png">
B. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/19-216-2.png">
C. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/19-216-3.png">
D. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/19-216-4.png">
Answer» B. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/19-216-2.png">
Discussion