MCQOPTIONS
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MCQOPTIONS
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.
| 7801. |
Depth of penetration does not depend on frequency. |
| A. | True |
| B. | False |
| Answer» C. | |
| 7802. |
In TE mode of waveguide Ez = 0 |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7803. |
The primary constants of a transmission line are |
| A. | R and L |
| B. | R, L and C |
| C. | R and C |
| D. | R, L, G and C |
| Answer» E. | |
| 7804. |
Assertion (A): Slotted line is frequently used for microwave measurements.Reason (R): The unknown impedance is mounted at the end of slotted line. |
| 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 | |
| 7805. |
Fibers have numerical aperture (NA) in the range of 0.15 to 0.4 Fibers with higher NA value would have |
| A. | reduced losses |
| B. | high bandwidth |
| C. | reduced losses and low bandwidth |
| D. | more losses and low bandwidth |
| Answer» E. | |
| 7806. |
Slotted line can be used for measurement of high frequencies |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7807. |
In a waveguide the dielectric region is generally |
| A. | air |
| B. | magnetic material |
| C. | brass |
| D. | mica |
| Answer» B. magnetic material | |
| 7808. |
Z0 = (Zoc Zsc)0.5 |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7809. |
What is the numerical aperture an optical fiber when critical angle is 30 ? |
| A. | 0.5 |
| B. | 0.704 |
| C. | 0.866 |
| D. | 0.2 |
| Answer» B. 0.704 | |
| 7810. |
A line of length slightly less than and short circuited at far end behaves as |
| A. | inductance L |
| B. | capacitance C |
| C. | L and C in series |
| D. | L and C in parallel |
| Answer» B. capacitance C | |
| 7811. |
In a microwave power measurement using bolometer, the principle of working is variation of |
| A. | inductance with absorption of power |
| B. | resistance with absorption of power |
| C. | capacitance with absorption of power |
| D. | cavity dimension with heat generated by power |
| Answer» C. capacitance with absorption of power | |
| 7812. |
The effect of earth's magnetic field on radiowaves is minimum when |
| A. | the electric field lines of radio waves and flux line of earth's magnetic field are in the same direction |
| B. | the electric field lines of radio waves and flux lines of earth's magnetic field are at right angles |
| C. | the electric field lines of radiowaves and flux lines of earth's magnetic field oppose each other |
| D. | both (b) and (c) |
| Answer» B. the electric field lines of radio waves and flux lines of earth's magnetic field are at right angles | |
| 7813. |
A line of characteristic impedance Z0 branches into two line each with characteristic impedance Z0. The refracted voltage is |
| A. | zero |
| B. | infinite |
| C. | equal to incident voltage |
| D. | two third of incident voltage |
| Answer» E. | |
| 7814. |
The most commonly used magnetron is |
| A. | cylindrical |
| B. | parallel plate |
| C. | inclined plate |
| D. | flat plate |
| Answer» B. parallel plate | |
| 7815. |
A line is excited by a 100 V, 200 ohm source and is terminated by 100 resistance. If the voltage on line reaches steady value in 80 ns, the natural resonant frequency is |
| A. | 100 MHz |
| B. | 50 MHz |
| C. | 12.5 MHz |
| D. | 6.25 MHz |
| Answer» D. 6.25 MHz | |
| 7816. |
Hollow waveguides are used as transmission lines at frequencies |
| A. | above 1 GHz |
| B. | above 5 GHz |
| C. | above 10 MHz |
| D. | above 1 MHz |
| Answer» C. above 10 MHz | |
| 7817. |
The following components are used to measure power output of a 2 kW TWT amplifier TWTLow pass/High pass filterLow power 20 dB attenuator40 dB directional coupler with matched loadPower meter. The correct sequence of connections of these components is: |
| A. | 1, 4, 2, 3, 5 |
| B. | 1, 3, 4, 2, 5 |
| C. | 1, 2, 4, 3, 5 |
| D. | 1, 4, 3, 2, 5 |
| Answer» C. 1, 2, 4, 3, 5 | |
| 7818. |
In directional coupler of the given figure, the terms |S14| and |S23| of scattering matrix are nearly |
| A. | 1 each |
| B. | 0.5 each |
| C. | 0.1 each |
| D. | 1 and 0.5 respectively |
| Answer» B. 0.5 each | |
| 7819. |
Which part of radio spectrum is more crowded? |
| A. | Lower frequency part |
| B. | Higher frequency part |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» E. | |
| 7820. |
Assertion (A): A line of length slightly more than and open circuited at far end is equivalent to an inductive reactance.Reason (R): A line of length slightly more than and short circuited at far end behaves as a capacitive reactance. |
| 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 | |
| 7821. |
A line of length slightly longer than and open circuited at far end behaves as |
| A. | inductance L |
| B. | capacitance C |
| C. | L and C in series |
| D. | L and C in parallel |
| Answer» B. capacitance C | |
| 7822. |
A microwave junction is matched at all ports if the S matrix |
| A. | has all diagonal elements zero |
| B. | has all diagonal elements equal but not zero |
| C. | has all diagonal elements complex |
| D. | is Hermitian |
| Answer» B. has all diagonal elements equal but not zero | |
| 7823. |
Reflection from the object to be measured is significant only when the wavelength is |
| A. | much bigger than the size of object |
| B. | much smaller than the size of object |
| C. | almost of the size of object |
| D. | either (a) or (c) |
| Answer» C. almost of the size of object | |
| 7824. |
Consider the following test signal patterns RampGrillGrey shadesSine pulsePicture line up generating equipment Which of the above are used in TV studios? |
| A. | All |
| B. | 1, 2 and 3 only |
| C. | 1, 2 and 5 only |
| D. | 2, 3, 4 and 5 only |
| Answer» B. 1, 2 and 3 only | |
| 7825. |
Beam width of an antenna is expressed in |
| A. | metres |
| B. | degrees |
| C. | ratio of two powers |
| D. | ratio of two angles |
| Answer» C. ratio of two powers | |
| 7826. |
Some possible disadvantages of high level modulation in TV transmitters are Video monitor has to supply high video voltages upto several hundred volts into highly capacitive loads drawing high current at video frequenciesThe grid modulated stage presents a varying load to its driverThe linearity and high video driving power present design problems Out of above which are true? |
| A. | 1 only |
| B. | 1 and 2 only |
| C. | 1, 2 and 3 |
| D. | 2 and 3 only |
| Answer» D. 2 and 3 only | |
| 7827. |
In broadcast television, the number of lines per frame is chosen to be odd number to |
| A. | reduce the required bandwidth |
| B. | improve resolution |
| C. | reduce peak power requirement |
| D. | make interlacing easier |
| Answer» E. | |
| 7828. |
In a picture tube, the video signal is applied to |
| A. | cathode |
| B. | grid |
| C. | any anode |
| D. | either cathode or grid |
| Answer» B. grid | |
| 7829. |
If frames are repeated at 60 Hz and each frame has 525 lines, the time for scanning one horizontal line (for progressive scanning and no interlacing) is about |
| A. | 320 s |
| B. | 32 s |
| C. | 3.2 s |
| D. | 0.32 s |
| Answer» C. 3.2 s | |
| 7830. |
Which of the following amplifiers is used for impedance matching? |
| A. | CE |
| B. | CC |
| C. | CB |
| D. | Push pull |
| Answer» C. CB | |
| 7831. |
Which of the following amplifiers has highest output impedance? |
| A. | CE |
| B. | CB |
| C. | CC |
| D. | Push pull |
| Answer» C. CC | |
| 7832. |
In a superheterodyne receiver, having no RF amplifier, the IF is 455 kHz. The image frequency at 1000 kHz is |
| A. | 1455 kHz |
| B. | 545 kHz |
| C. | 1910 kHz |
| D. | 90 kHz |
| Answer» C. 1910 kHz | |
| 7833. |
Audio tapes have two tracks each 2.5 mm wide. |
| A. | True |
| B. | False |
| Answer» C. | |
| 7834. |
Which of the following amplifiers has a voltage gain of less than 1? |
| A. | CE |
| B. | CC |
| C. | CB |
| D. | CE or CB |
| Answer» C. CB | |
| 7835. |
In high power radars, which of the following are used for switching? |
| A. | Power diode |
| B. | Power BJT |
| C. | Power MOSFET |
| D. | Thyristor |
| Answer» E. | |
| 7836. |
A remote control for TV uses |
| A. | LED in receiver and photodiode in transmitter |
| B. | LED in transmitter and photodiode in receiver |
| C. | LED in both transmitter and receiver |
| D. | Photodiode in both transmitter and receiver |
| Answer» C. LED in both transmitter and receiver | |
| 7837. |
In the television system in India, the aspect ratio is |
| A. | 4 : 3 |
| B. | 3 : 4 |
| C. | 5 : 4 |
| D. | 4 : 5 |
| Answer» B. 3 : 4 | |
| 7838. |
A sequence x(n) with the z transform X(z) = z4 + z2 - 2z + 2 - 3z - 4 is applied as an input to a linear, time invariant system with the impulse response h(n) = 2 (n - 3) where The output at n = 4 is |
| A. | - 6 |
| B. | zero |
| C. | 2 |
| D. | - 4 |
| Answer» C. 2 | |
| 7839. |
The name modem is a contraction of terms modulator demodulator. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7840. |
The use of SSB |
| A. | halves the bandwidth required for transmission |
| B. | does not affect the bandwidth for transmission |
| C. | decreases the bandwidth required for transmission by 25% |
| D. | decreases the bandwidth required for transmission by 66.6% |
| Answer» B. does not affect the bandwidth for transmission | |
| 7841. |
If a signal voltage Vs is accompanied by a noise voltage Vn the signal to noise ratio is |
| A. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/501-130-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/501-130-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/501-130-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/501-130-4.png"> |
| Answer» B. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/501-130-2.png"> | |
| 7842. |
Consider the draw backs Slope overloadSerration noiseGranular noise Which of these draw backs does Delta modulation have? |
| A. | 1 and 2 only |
| B. | 2 and 3 only |
| C. | 1 and 3 only |
| D. | 1, 2, 3 |
| Answer» D. 1, 2, 3 | |
| 7843. |
Video signals are transmitted through |
| A. | amplitude modulation |
| B. | frequency modulation |
| C. | either amplitude or frequency modulation |
| D. | neither amplitude nor frequency modulation |
| Answer» B. frequency modulation | |
| 7844. |
A TV receiver has 20 kV EHT supply and total beam current (for 3 electron guns) of 1500 A. The power handled by IHVT is |
| A. | 3 W |
| B. | 30 W |
| C. | 300 W |
| D. | 0.3 W |
| Answer» C. 300 W | |
| 7845. |
The filter circuit for feeding tweeter has |
| A. | an inductance in series and a capacitance in parallel |
| B. | a capacitance in series and an inductance in parallel |
| C. | a resistance in series and a capacitance in parallel |
| D. | a capacitance in series and a resistance in parallel |
| Answer» C. a resistance in series and a capacitance in parallel | |
| 7846. |
It is required to increase the maximum range of a radar by a factor of two. The peak power transmitted in the radar system has to be increased by a factor of |
| A. | 2 |
| B. | 4 |
| C. | 8 |
| D. | 16 |
| Answer» B. 4 | |
| 7847. |
Armstrong F.M. transmitter performs frequency multiplication in stages |
| A. | to increase the overall S/N |
| B. | for convenience |
| C. | to reduce the bandwidth |
| D. | to find the desired value of carrier frequency with frequency deviation |
| Answer» E. | |
| 7848. |
A source generates three symbols with probabilities 0.25, 0.25, 0.50 at a rate of 3000 symbols per second. Assuming independent generation of symbols, the most efficient source encoder would have average bit rate is as |
| A. | 6000 bits/sec |
| B. | 4500 bits/sec |
| C. | 3000 bits/sec |
| D. | 1500 bits/sec |
| Answer» C. 3000 bits/sec | |
| 7849. |
The radio receivers mostly used now a days are |
| A. | TRF receivers |
| B. | super heterodyne receivers |
| C. | CW receivers |
| D. | pulsed receivers |
| Answer» C. CW receivers | |
| 7850. |
The reactance of coupling capacitors, for DC quantities, is |
| A. | zero |
| B. | low |
| C. | infinite |
| D. | zero or low |
| Answer» D. zero or low | |