Question with Answer BSNL JE 

1.   ZL = 200Ω and it is desired that Zi = 50Ω. The quarterwave transformer should have a characteristics impedance of :
(a) 100Ω                                                        
(b) 40Ω
(c) 10,000Ω                                                       
(d) 4Ω                                                                  
Ans (c)
2.   In a silicon crystal, the arrangement of atoms repeats periodically. This type of material is classified as :
(a) Amorphous and non-crystalline
(b) non-crystalline and epitaxial
(c) epitaxial and single crystal
(d) amorphous and single crystal                       
Ans (b)
3.   A sinusoidal waveform is mathematically represented by :
(a) an EVEN function
(b) an ODD function
(c) a function that is EVEN as well as HALF WAVE SYMMETRIC
(d) an infinite number of source pulses.        
Ans (c)
4.   In class-A operation of an amplifier, the current flows through the active device for :
(a) Whole of the input cycle
(b) half of the input cycle
(c) more than half of the input cycle
(d) less than half of the input cycle                      
Ans (a)
5.   Harmonic distortion in amplifiers is caused by :
(a) nonlinearity of the active device
(b) defective active device
(c) presence of shot noise
(d) positive feedback from output to input                 
Ans (d)
6.   With the controversial notation X = AX + BU for the state description of a linear time-in-varient network, examine the validity of the following statements relating to the matrix A :
1. A is symmetrical if the network is reciprocal
2. The sum of the natural frequencies of the network is equal to the determined A
Which of these statements is/are true ?
(a) Both 1 and 2                                                           
(b) 1 only
(c) 2 only                                                             
(d) Neither 1 nor 2                                          
Ans (c)
7.   In a certain code language QUESTION is written as SOIQNEUT. How is MOTHER written in that code again ?
(a) TEMROH                                                     
(b) HEMROT
(c) TERMOH                                                           
(d) REHTOM                                                      
Ans (d)
8.  The class of amplifier operation characterized by highest efficiency, high distortion is :
(a) Class – A                                                                
(b) Class – B       
(c) Class – C                                                               
(d) Class – AB                                                    
Ans (c)
9.   Consider the following :
1. Pulse- position modulation                                                    
2. Pulse-code modulation
3. Pulse-width modulation
Which of these communications are not digital ?
(a) 1 and 2                                                                     
(b) 2 and 3
(c) 1 and 3                                                                
(d) 1, 2 and 3                                                     
Ans (c)
10.   Consider the following statements :
1. Intermediate-frequency (IF) amplifier is designed for bandwidth of a few kHz
at a centre frequency of a few hundred kHz for voice-modulated signals.
2. IF amplifier is designed for a frequency of 6 MHz at a centre frequency of 40 MHz for TV receivers.
3. Tuned amplifiers are used for IF amplifier.
Which of these statements is/are correct ?
(a) 1 only                                                                 
(b) 3 only
(c) 2 and 3                                                                 
(d) 1, 2 and 3                                                     
Ans (d)
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