BEL Placement Paper-Electronics I

8/12/2019 BEL Placement Paper-Electronics I

1/22

Paper: BEL Placement Paper (Technical-Electronics Ist)

1. The gray code equivalent of binary 1100 is

a. 1011 b. 1101 c. 1010 d. 1100

2. A Multiplexer has

a. Multiple inputs and single output

b. Single input and Multiple outputs

c. Multiple inputs and Multiple outputs

d. Multiple inputs for Storage of Data

. A binary half adder

a. Adds t!o binary digits and produces their su" and carry

b. Adds half the su" to the carry

c. Adds t!o binary digits and carry fro" previous addition

d. Adds t!o binary digits at half the speed

#. An index register in a co"puter is for

a. Arith"etic and logic functions

b. Storage of results

c. Modifying the address

d. $ounting the no of progra""es

%. An exa"ple of volatile "e"ory is

a. &AM b. &'M c. ()&'M d. Magnetic tape

*. +arrier voltage in a ),- unction is caused by

a. Ther"ally generated electrons and holes

b. Diffusion of "aority carriers across the unction


2/22

c. Migration of "inority carriers across the unction

d. /lo! of drift current

. The te"perature coefficient of an intrinsic se"iconductor is

a. )ositive b. -egative c. ero d. i3e "etals

4. A silicon transistor has a lea3age current 1cbo 5 1 "a. 6f the te"p. rises by %0o $ thelea3age current !ill be

a. 0 "a b. 2"a c. %0"a d. no change

7. The noise figure of an ideal a"plifier in decibel is

a. 0.% b. 0 c. 1 d. 10

10. The rise ti"e of an a"plifier is 200 nsec. 6ts band!idth is

a. 0M89 b. 1#0M89 c. 100M89 d. 1.%Mh9

11. M'S/(T operates in

a. Depletion "ode only

b. (nhance"ent "ode only

c. Depletion and enhance"ent "ode

d. -one of these of the above

12. A device !hich behaves li3e S$&s is

a. :;T b. Triac c. M'S/(T d. S&D

1. A plate "odulated class $ &/ a"plifier produces 100 "odulation. The "odulating audio a"plifier supplies approxi"ately

a. 2%


3/22

1%. -oise generated by a resistor is dependent on

a. 6ts alue

b. 6ts te"perature

c. +oth value and te"p

d. -one of these

1*. A 2 channel 4 bit )$M syste" sa"ples at 4


4/22

d. o!est co""unication frequency possible

21. The cathode ray oscilloscope can be used to "easure

a. /requency b. Ti"e interval c. oltage d. All the above

22. A !ein bridge is used for "easure"ent of

a. &esistance b. $apacitance c. 6nductance d. Audio frequency

2. The fra"e rate per second used in 6ndia T is

a. *0 b. %0 c. 2% d. 0

2#. 8/ signals are propagated

a. ia the ionosphere

b. Along the ground

c. Through the troposphere

d. +y reflection in ionosphere

2%. The i"pedance of a ele"ent yagi antenna is around

a. %= b. 00= c. %0= d. 100=

2*. A )6- diode is "icro!ave

a. 'scillator b. Mixer c. Detector d. S!itch

2. A trans"ission line of S=& 2 has a reflection coefficient

a. 0.2% b. 0.% c. % d. 0

24. Micro!ave repeaters are typically

a. 2% b. %0 c. % d. 100


5/22

c. Space Diversity

d. /requency Diversity

0. /requency in the :8/ range is propagate by !aves of

a. Bround b. s3y c. Space d. Surface

1. A duplexer is used to

a. &eceive t!o signals in one antenna

b. )revent interference bet!een t!o antenna

c. Mix t!o signals to the sa"e antenna

d. Allo! one antenna for both trans"ission and reception

2. Strapping is used in a "agnetron to

a. )revent "ode u"ping

b. &educe frequency drift

c. (nsure proper bunching

d. Dissipate heat

. A rectangular !aveguide behaves li3e a filter of

a. +and pass b. 8igh pass c. o! pass d. +and stop

#. The signal propagation ti"e in "illiseconds for a geosynchronous satellite is

a. %#0 b. 20 c. 1% d. 100

%. The silicon solar cell is a

a. )hoto conductive

b. )hoto e"issive

c. )hoto voltaic

d. )hoto resistive


6/22

*. /or the national T and ratio net!or3? 6-SAT,6+ uses

a. #00M89 b. 2.%B89 c. 2.% and %B89 d. # and * B89

. A typical fibre,optic detector is

a. Step recovery diode

b. ight e"itting diode

c. Avalanche photo diode

d. /ield effect transistor

4. A "ode" is a device used for

a. Digiti9ing voice data

b. Trans"ission of data on lines

c. Modulating and de"odulating signals sent on a line

d. Suppressing noise interference

7. The "ost effective anti,a""ing technique is

a. /requency hopping

b. Spread Spectru"

c. /requency synthesis

d. +urst trans"ission

#0. Mono,"ode is a ter" used in

a. /ibre,optics

b. &adar

c. Satellite co""unication

d. Magnetics

#1. Monopulse technique is used in


7/22

a. &adar

b. &adio relay

c. Data co""unication

d. /ibre,optics

#2. 8D$ is a ter" for

a. Data co""unication protocol

b. Synchroni9ing pulses

c. Bain control in receivers

d. (rror chec3ing

#. A gate!ay

a. 6s a place !here radars are connected

b. )er"its dissi"ilar net!or3s to co""unicate

c. +ifurcates the &/ path of a trans"itter

d. 6s a feeder cable

##. (thernet is a na"e of

a. Mediu" of co"puter co""unication

b. -et!or3 for co"puter co""unication

c. )rocedures for co"puter co""unication net!or3

d. Soft!are for co"puter co""unication

#%. 6f several stations in a net!or3 !ant to use a single channel !ithout interfering !ithone another? the technique used is called

a. $arrier sense

b. )hanto",free9e


8/22

c. )ac3et s!itching

d. Multiplexing

#*. 6n a "onolithic 6$? resistors are for"ed fro"

a. $era"ic "aterials

b. $opper

c. ),type se"iconductor

d. Alu"iniu" deposition

#. 6$s "ade by sputtering of "aterials on a cera"ic substrate are called

a. Monolithic b. 8ybrid c. Thic3 fil" d. Thin fil" #4. T!o coils Cinductors connected in series have a co"bined inductance of 1%"8.=hen ter"inals of one of the coils are reversed and connected to the other? the co"binedinductance is "easured to be 7"8. =hat is the value of "utual inductance

a. 1.%"8 b."8 c.*"8 d.12"8

#7. 6f a parallel $ circuit is excited at frequency less than its resonant frequency? thenature of its effective i"pedance is

a. &esistive b. 6nductive c. $apacitive d. -one of these of these

%0. The !ave length of 1 Biga hert9 frequency signal is

a. 10c" b. 0c" c. c" d. 1c"

%1. =hich of the follo!ing "icro!ave tubes can be considered as broad band devices

a. Magnetrons

b.


9/22

%. The "ost i"portant feature of $M'S fa"ily of 6$s is

a. 8igh speed

b. S"all si9e

c. o! po!er consu"ption

d. o! input i"pedance

%#. =hat is the resolution of 4 bit AGD converter if its full scale voltage is 10v

a. 0.02v b. 0.01 c. 0.07v d. 0.04v

%%. =hat value of resistance is to be used in S+ of # bit !eighted ladder DGA converter

if MS+ has 10 3= resistora. 1*03 b. 403 c. 2#03 d. 1003

%*. The pulse !idth of a radar trans"itter is 0.*" sec. and the pulse repetition rate is00 89. The average po!er "easured is #20 !atts. =hat is the pea3 po!er

a. 100


10/22

a. o! output i"pedance

b. $an sin3 "ore current

c. 'scillations avoided

d. -one of these

*0. The capacitance value of a varactor is controlled by

a. A reverse voltage applied to it

b. A series resistance

c. arying its supply voltage

d. $urrent through the device

*1. (lectron volt is equivalent to

a. .4 I 10,20 erg

b. 1.*02 I 10,12 erg

c. 1.*02 I 10,14 erg

d. 1.*02 I 10,1* erg

*2. The 3inetic energy of photo electrons e"itted by a photo sensitive surface dependson

a. 6ntensity of the incident radiation

b. =avelength of the incident radiation

c. Angle of incident of radiation

d. Surface conditions of the surface

*. /lux is expressed in radio,"etric syste" in

a. u"ens

b. )hotons


11/22

c. =atts

d. $andles

*#. 6n a three,phase bridge rectifier circuit? the ripple frequency is

a. Sa"e as line frequency

b. T!ice the line frequency

c. Thrice the line frequency

d. Six ti"es the line frequency

*%. (nergy stored in a capacitor as a function of voltage is given by

a. $2b. 12G2$

c. J $2

d. 1G2$

**. The operational a"plifier used in analog co"puters have usually open loop flat gainapproxi"ately upto

a. 1M89 b. 100M89 c. 10M89 d. 0.1M89

*. An oscillator of %0 M89 is fed !ith a pulse of rise ti"e 2 n sec. The rise ti"e ofthe displayed !avefor" is approxi"ately

a. 1 n sec b. 2.2 n sec c. 2.0 n sec d. 1. n sec

*4. A radar trans"its a pea3 po!er of 100


12/22

d. $hange of frequency

0. Micro!ave tube based on velocity "odulation principle is

a.


13/22

*. The usage of "icro sec for defining e"phasis is a standard practice but this "icrosec definition "eans

a. d+ point of the net!or3 "eans

b. "id point of the net!or3 response

c. roll off the net!or3 response

d. the stop band ripple of the net!or3 response

. Delayed AB$ is applied

a. /or all singal strength

b. /or singal strength exceeding a specified li"itc. /or lo! singal strength

d. /or /M receiver

4. Selectivity "eans

a. +and!idth

b. Bain

c. Modulation index

d. -one of these

7. -arro! band!idth broadcast reduces

a. The quality and noise

b. @uality alone

c. -oise alone

d. @uality and intelligibility

40. Squelch "eans 3eeping the receiver

a. '- in the absence of carrier


14/22

b. '// in the absence of carrier

c. To re"ove AB$

d. 6ncrease the AB$

41. et be the series i"pedance and K be the shunt ad"ittance of the trans"issionline? then the characteristic i"pedance

a. L,K b.L,KG c. L,GK d.All the above

42. -oise figure of an a"plifier is defined as

a. 6nput S-& output S-&

b. 6nput S-& G output S-&

c. 'utput S-& G input S-&

d. 6nput S-& G gain

4. A broadcast radio trans"itter radiates 10 of"odulation is approxi"ately

a. 0.1> b. 40.1> c. *%.1> d. 10.0>

4%. 6n AM trans"ission antenna current is 4 A"pere at 9ero "odulation index. At 40>"odulation index the antenna current !ill be

a. 10.00A b. 4.2A c. 7.17A d. 7.7A

4*. 6f t!o sine !aves are a"plitude "odulated !ith "odulation index "1 and "2? theeffective "odulation index is

a. L, "12G"22

b. L, "1 "2

c. L, "12"22


15/22

d. L, "22G"12

4. 6f it is trans"itted current and 6c is trans"itter current at 9ero "odulation index andthe trans"itted current at "odulation index of " !ill

a. 6t 5 6c L,E1"F

b. 6t 5 6c L,E1"2F

c. 6t 5 6c L,E1"G22F

d. 6t 5 6cL,1"2

44. 6f &r is the radiation resistance and &d is the lu"ped resistance? then the antennaefficiency is given as H

a. C&r , &d G C&r &db. C&r &d G C&r H &d

c. &r G C&r &d

d. &d G C&r &d

47. 6n end fire array? the current

a. Magnitude and phase in each ele"ent is the sa"e

b. Magnitude is the sa"e but phase is different in each ele"ent

c. Magnitude is different but no phase difference in each ele"ent

d. Magnitude and phase are different in each ele"ent

70. 6n a board side array? the current

a. Magnitude and phase in each ele"ent is the sa"e

b. Magnitude is the sa"e but phase is different

c. Magnitude is different but no phase difference in each ele"ent

d. Magnitude and phase are different in each ele"ent

71. +ea" !idth of the 2 "etre paraboloid reflector at * B89 is


16/22

a. #.%o

b. 7.2%o

c. .%o

d. .%o

72. The cut of !ave length for T( "? n "ode is in a !ave guide of di"ension aIb is

a. 2GL,C"Ga2 CnGb2

b. 2L, E"GaF2 EnGbF2

c. L,C"Ga2 CnGb2 G2

d. L, E"GaF2 EnGbF2 7. /or the standard rectangular !aveguide di"ension of #I2 c" the off !avelength forTM11 "ode is approxi"ately

a. 1.44c" b. .%*c" c. 1.*42c" d. 2.%#*c"

7#. 6n 6M)ATT diode? the voltage and current are

a. 6n phase

b. 'ut off phase by 70o

c. 'ut off phase by 140o


7%. =hich of the follo!ing state"ent is true

a. Tunnel diode N 6M)ATT diode are negative resistance devices

b. Tunnel diode is positive resistance device and the 6M)ATT diode is negativeresistance device

c. Tunnel diode is negative resistance device and the 6M)ATT diode is positiveresistance device


7*. 6n a SS+ "odulation syste" !ith 100> "odulation index the po!er saving !ill be


17/22

a. %G* of carrier po!er

b. 2G4 of carrier po!er

c. %G12 of the carrier po!er

d. J of the carrier po!er

7. 6n SS+ "odulation the "odulation index is increased fro" 0.% to 1.0? then thepo!er !ill be increased by

a. 2 ti"es b. # ti"es c. 1* ti"es d. 2 ti"es

74. 700 rp" is equal to

a. 7#.2 radGsecb. #.1 radGsec

c. 144.# radGsec

d. 1*.2 radGsec

77. Darlington pair is used to

a. 6ncrease the voltage gain

b. 6ncrease the current gain

c. Decrease voltage gain

d. Decrease current gain

100. The transfer function of the syste" sho!n is

a. BCs G O1 8CsP

b. BCs 8Cs G O1 BCs 8CsP

c. BCs G O1 BCs 8CsP d. BCs G BCs 8Cs

(lectronics,6 Ans!ers


18/22

1. c

2. a

. a

#. c

%. a

*. b

. b

4. b

7. b10. d

11. c

12. b

1. b

1#. d

1%. c

1*. a

1. c

14. d

17. c

20. b

21. d

22. d

2. c


19/22

2#. b

2%. b

2*. d

2. c

24. b

27. d

0. c

1. d

2. a. b

#. c

%. c

*. d

. c

4. c

7. a

#0. a

#1. a

#2. a

#. b

##. b

#%. d

#*. c


20/22

#. d

#4. a

#7. b

%0. b

%1. d

%2. b

%. c

%#. c

%%. b%*. c

%. b

%4. b

%7. a

*0. a

*1. b

*2. b

*. a

*#. b

*%. c

**. d

*. c

*4. b

*7. d


21/22

0. a

1. a

2. a

. b

#. a

%. b

*. a

. b

4. a7. a

40. b

41. c

42. b

4. a

4#. a

4%. c

4*. c

4. c

44. c

47. b

70. a

71. c

72. a


22/22

7. b

7#. c

7%. a

7*. a

7. b

74. b

77. b

100. c

BEL Placement Paper-Electronics I

Documents

Transcript of BEL Placement Paper-Electronics I