Questions with Answer BSNL JE

1. One of the following microwave diodes is suitable for very low-power
oscillators only :
(a) Tunnel                                                                                              (b) LSA
(c) Gunn                                                                                                 (d) IMPATT                                                     
 Ans (a)
2.   A solid conducting slab falls under gravity. However, after some time, it tends
to acquire constant speed. This is due to :
(a) Air friction                                                                                       (b) conduction current
(c) both the above                                                                               (d) none of the above                                   
 Ans (c)
3.   Two’s complement of a given 3 or more bit binary number of non-zero magnitude
is the same as the original number if all bits except the :
(a) MSB are zeros                                                                                 (b) LSB are zeros
(c) MSB are ones                                                                                  (d) LSB are ones                                                
 Ans (b)
4.   A transfer function having open right half plane zeros is a/an :
(a) Minimum phase function
(b) Non-minimum phase function
(c) Unstable function
(d) Constant phase function                                                                                                                                          
 Ans (b)
5.   With variable reluctance tachometer having 60 rotor teeth, the counter records 3600
counts per minute. The device speed, in r.p.m, would be :
(a) 36                                                                                                      (b) 60
(c) 360                                                                                                   (d) 3600                                                        
  Ans (b)
6.   Consider the following statements :
1. Ultrasonic technique cannot be used for measurement of flow of a liquid having
air bubbles in it.
2. Attenuation of ultrasonic signal is less in air compared to that in liquid.
Of these statements :
(a) 2 is false and 1 is true
(b) 1 and 2 are true
(c) 2 is true and 1 is false
(d) 1 and 2 are false                                                                                                                                                           
Ans (b)
7.   Diversity reception is used to :
(a) Increase receiver sensitivity
(b) Improve receiver selectivity
(c) Overcome degrading effect of fading
(d) Overcome degrading effect of receiver detuning                                                                                                
 Ans (c)
8.   A waveguide section in a microwave circuit will act as a :
(a) low-pass filter                                                                                 (b) band-pass filter
(c) high-pass filter                                                                                (d) band-stop filter                                           
 Ans (c)
9.   If the peak transmitted power in a radar system is increased by a factor 16, the
maximum range will be increased by a factor of :
(a) 16                                                                                                      (b) 2
(c) 8                                                                                                        (d) 4                                                                
 Ans (b)
10.   A magnetron whose oscillating frequency is electronically adjustable over a wide
range is called a :
(a) Coaxial magnetron                                                                        
(b) Dither-tuned magnetron
(c) frequency-agile magnetron
(d) VTM                                                                                                                                                                            
 Ans(d)
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